creation_sourcecode: {{
    "language": "Solidity",
    "sources": {
      "@openzeppelin/contracts/access/Ownable.sol": {
        "content": "// SPDX-License-Identifier: MIT\n\npragma solidity >=0.6.0 <0.8.0;\n\nimport \"../utils/Context.sol\";\n/**\n * @dev Contract module which provides a basic access control mechanism, where\n * there is an account (an owner) that can be granted exclusive access to\n * specific functions.\n *\n * By default, the owner account will be the one that deploys the contract. This\n * can later be changed with {transferOwnership}.\n *\n * This module is used through inheritance. It will make available the modifier\n * `onlyOwner`, which can be applied to your functions to restrict their use to\n * the owner.\n */\nabstract contract Ownable is Context {\n    address private _owner;\n\n    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);\n\n    /**\n     * @dev Initializes the contract setting the deployer as the initial owner.\n     */\n    constructor () internal {\n        address msgSender = _msgSender();\n        _owner = msgSender;\n        emit OwnershipTransferred(address(0), msgSender);\n    }\n\n    /**\n     * @dev Returns the address of the current owner.\n     */\n    function owner() public view virtual returns (address) {\n        return _owner;\n    }\n\n    /**\n     * @dev Throws if called by any account other than the owner.\n     */\n    modifier onlyOwner() {\n        require(owner() == _msgSender(), \"Ownable: caller is not the owner\");\n        _;\n    }\n\n    /**\n     * @dev Leaves the contract without owner. It will not be possible to call\n     * `onlyOwner` functions anymore. Can only be called by the current owner.\n     *\n     * NOTE: Renouncing ownership will leave the contract without an owner,\n     * thereby removing any functionality that is only available to the owner.\n     */\n    function renounceOwnership() public virtual onlyOwner {\n        emit OwnershipTransferred(_owner, address(0));\n        _owner = address(0);\n    }\n\n    /**\n     * @dev Transfers ownership of the contract to a new account (`newOwner`).\n     * Can only be called by the current owner.\n     */\n    function transferOwnership(address newOwner) public virtual onlyOwner {\n        require(newOwner != address(0), \"Ownable: new owner is the zero address\");\n        emit OwnershipTransferred(_owner, newOwner);\n        _owner = newOwner;\n    }\n}\n"
      },
      "@openzeppelin/contracts/math/SafeMath.sol": {
        "content": "// SPDX-License-Identifier: MIT\n\npragma solidity >=0.6.0 <0.8.0;\n\n/**\n * @dev Wrappers over Solidity's arithmetic operations with added overflow\n * checks.\n *\n * Arithmetic operations in Solidity wrap on overflow. This can easily result\n * in bugs, because programmers usually assume that an overflow raises an\n * error, which is the standard behavior in high level programming languages.\n * `SafeMath` restores this intuition by reverting the transaction when an\n * operation overflows.\n *\n * Using this library instead of the unchecked operations eliminates an entire\n * class of bugs, so it's recommended to use it always.\n */\nlibrary SafeMath {\n    /**\n     * @dev Returns the addition of two unsigned integers, with an overflow flag.\n     *\n     * _Available since v3.4._\n     */\n    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {\n        uint256 c = a + b;\n        if (c < a) return (false, 0);\n        return (true, c);\n    }\n\n    /**\n     * @dev Returns the substraction of two unsigned integers, with an overflow flag.\n     *\n     * _Available since v3.4._\n     */\n    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {\n        if (b > a) return (false, 0);\n        return (true, a - b);\n    }\n\n    /**\n     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.\n     *\n     * _Available since v3.4._\n     */\n    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {\n        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the\n        // benefit is lost if 'b' is also tested.\n        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522\n        if (a == 0) return (true, 0);\n        uint256 c = a * b;\n        if (c / a != b) return (false, 0);\n        return (true, c);\n    }\n\n    /**\n     * @dev Returns the division of two unsigned integers, with a division by zero flag.\n     *\n     * _Available since v3.4._\n     */\n    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {\n        if (b == 0) return (false, 0);\n        return (true, a / b);\n    }\n\n    /**\n     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.\n     *\n     * _Available since v3.4._\n     */\n    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {\n        if (b == 0) return (false, 0);\n        return (true, a % b);\n    }\n\n    /**\n     * @dev Returns the addition of two unsigned integers, reverting on\n     * overflow.\n     *\n     * Counterpart to Solidity's `+` operator.\n     *\n     * Requirements:\n     *\n     * - Addition cannot overflow.\n     */\n    function add(uint256 a, uint256 b) internal pure returns (uint256) {\n        uint256 c = a + b;\n        require(c >= a, \"SafeMath: addition overflow\");\n        return c;\n    }\n\n    /**\n     * @dev Returns the subtraction of two unsigned integers, reverting on\n     * overflow (when the result is negative).\n     *\n     * Counterpart to Solidity's `-` operator.\n     *\n     * Requirements:\n     *\n     * - Subtraction cannot overflow.\n     */\n    function sub(uint256 a, uint256 b) internal pure returns (uint256) {\n        require(b <= a, \"SafeMath: subtraction overflow\");\n        return a - b;\n    }\n\n    /**\n     * @dev Returns the multiplication of two unsigned integers, reverting on\n     * overflow.\n     *\n     * Counterpart to Solidity's `*` operator.\n     *\n     * Requirements:\n     *\n     * - Multiplication cannot overflow.\n     */\n    function mul(uint256 a, uint256 b) internal pure returns (uint256) {\n        if (a == 0) return 0;\n        uint256 c = a * b;\n        require(c / a == b, \"SafeMath: multiplication overflow\");\n        return c;\n    }\n\n    /**\n     * @dev Returns the integer division of two unsigned integers, reverting on\n     * division by zero. The result is rounded towards zero.\n     *\n     * Counterpart to Solidity's `/` operator. Note: this function uses a\n     * `revert` opcode (which leaves remaining gas untouched) while Solidity\n     * uses an invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function div(uint256 a, uint256 b) internal pure returns (uint256) {\n        require(b > 0, \"SafeMath: division by zero\");\n        return a / b;\n    }\n\n    /**\n     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),\n     * reverting when dividing by zero.\n     *\n     * Counterpart to Solidity's `%` operator. This function uses a `revert`\n     * opcode (which leaves remaining gas untouched) while Solidity uses an\n     * invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function mod(uint256 a, uint256 b) internal pure returns (uint256) {\n        require(b > 0, \"SafeMath: modulo by zero\");\n        return a % b;\n    }\n\n    /**\n     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on\n     * overflow (when the result is negative).\n     *\n     * CAUTION: This function is deprecated because it requires allocating memory for the error\n     * message unnecessarily. For custom revert reasons use {trySub}.\n     *\n     * Counterpart to Solidity's `-` operator.\n     *\n     * Requirements:\n     *\n     * - Subtraction cannot overflow.\n     */\n    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\n        require(b <= a, errorMessage);\n        return a - b;\n    }\n\n    /**\n     * @dev Returns the integer division of two unsigned integers, reverting with custom message on\n     * division by zero. The result is rounded towards zero.\n     *\n     * CAUTION: This function is deprecated because it requires allocating memory for the error\n     * message unnecessarily. For custom revert reasons use {tryDiv}.\n     *\n     * Counterpart to Solidity's `/` operator. Note: this function uses a\n     * `revert` opcode (which leaves remaining gas untouched) while Solidity\n     * uses an invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\n        require(b > 0, errorMessage);\n        return a / b;\n    }\n\n    /**\n     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),\n     * reverting with custom message when dividing by zero.\n     *\n     * CAUTION: This function is deprecated because it requires allocating memory for the error\n     * message unnecessarily. For custom revert reasons use {tryMod}.\n     *\n     * Counterpart to Solidity's `%` operator. This function uses a `revert`\n     * opcode (which leaves remaining gas untouched) while Solidity uses an\n     * invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\n        require(b > 0, errorMessage);\n        return a % b;\n    }\n}\n"
      },
      "@openzeppelin/contracts/utils/Address.sol": {
        "content": "// SPDX-License-Identifier: MIT\n\npragma solidity >=0.6.2 <0.8.0;\n\n/**\n * @dev Collection of functions related to the address type\n */\nlibrary Address {\n    /**\n     * @dev Returns true if `account` is a contract.\n     *\n     * [IMPORTANT]\n     * ====\n     * It is unsafe to assume that an address for which this function returns\n     * false is an externally-owned account (EOA) and not a contract.\n     *\n     * Among others, `isContract` will return false for the following\n     * types of addresses:\n     *\n     *  - an externally-owned account\n     *  - a contract in construction\n     *  - an address where a contract will be created\n     *  - an address where a contract lived, but was destroyed\n     * ====\n     */\n    function isContract(address account) internal view returns (bool) {\n        // This method relies on extcodesize, which returns 0 for contracts in\n        // construction, since the code is only stored at the end of the\n        // constructor execution.\n\n        uint256 size;\n        // solhint-disable-next-line no-inline-assembly\n        assembly { size := extcodesize(account) }\n        return size > 0;\n    }\n\n    /**\n     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to\n     * `recipient`, forwarding all available gas and reverting on errors.\n     *\n     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost\n     * of certain opcodes, possibly making contracts go over the 2300 gas limit\n     * imposed by `transfer`, making them unable to receive funds via\n     * `transfer`. {sendValue} removes this limitation.\n     *\n     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].\n     *\n     * IMPORTANT: because control is transferred to `recipient`, care must be\n     * taken to not create reentrancy vulnerabilities. Consider using\n     * {ReentrancyGuard} or the\n     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].\n     */\n    function sendValue(address payable recipient, uint256 amount) internal {\n        require(address(this).balance >= amount, \"Address: insufficient balance\");\n\n        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value\n        (bool success, ) = recipient.call{ value: amount }(\"\");\n        require(success, \"Address: unable to send value, recipient may have reverted\");\n    }\n\n    /**\n     * @dev Performs a Solidity function call using a low level `call`. A\n     * plain`call` is an unsafe replacement for a function call: use this\n     * function instead.\n     *\n     * If `target` reverts with a revert reason, it is bubbled up by this\n     * function (like regular Solidity function calls).\n     *\n     * Returns the raw returned data. To convert to the expected return value,\n     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].\n     *\n     * Requirements:\n     *\n     * - `target` must be a contract.\n     * - calling `target` with `data` must not revert.\n     *\n     * _Available since v3.1._\n     */\n    function functionCall(address target, bytes memory data) internal returns (bytes memory) {\n      return functionCall(target, data, \"Address: low-level call failed\");\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with\n     * `errorMessage` as a fallback revert reason when `target` reverts.\n     *\n     * _Available since v3.1._\n     */\n    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {\n        return functionCallWithValue(target, data, 0, errorMessage);\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n     * but also transferring `value` wei to `target`.\n     *\n     * Requirements:\n     *\n     * - the calling contract must have an ETH balance of at least `value`.\n     * - the called Solidity function must be `payable`.\n     *\n     * _Available since v3.1._\n     */\n    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {\n        return functionCallWithValue(target, data, value, \"Address: low-level call with value failed\");\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but\n     * with `errorMessage` as a fallback revert reason when `target` reverts.\n     *\n     * _Available since v3.1._\n     */\n    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {\n        require(address(this).balance >= value, \"Address: insufficient balance for call\");\n        require(isContract(target), \"Address: call to non-contract\");\n\n        // solhint-disable-next-line avoid-low-level-calls\n        (bool success, bytes memory returndata) = target.call{ value: value }(data);\n        return _verifyCallResult(success, returndata, errorMessage);\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n     * but performing a static call.\n     *\n     * _Available since v3.3._\n     */\n    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {\n        return functionStaticCall(target, data, \"Address: low-level static call failed\");\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],\n     * but performing a static call.\n     *\n     * _Available since v3.3._\n     */\n    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {\n        require(isContract(target), \"Address: static call to non-contract\");\n\n        // solhint-disable-next-line avoid-low-level-calls\n        (bool success, bytes memory returndata) = target.staticcall(data);\n        return _verifyCallResult(success, returndata, errorMessage);\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n     * but performing a delegate call.\n     *\n     * _Available since v3.4._\n     */\n    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {\n        return functionDelegateCall(target, data, \"Address: low-level delegate call failed\");\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],\n     * but performing a delegate call.\n     *\n     * _Available since v3.4._\n     */\n    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {\n        require(isContract(target), \"Address: delegate call to non-contract\");\n\n        // solhint-disable-next-line avoid-low-level-calls\n        (bool success, bytes memory returndata) = target.delegatecall(data);\n        return _verifyCallResult(success, returndata, errorMessage);\n    }\n\n    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {\n        if (success) {\n            return returndata;\n        } else {\n            // Look for revert reason and bubble it up if present\n            if (returndata.length > 0) {\n                // The easiest way to bubble the revert reason is using memory via assembly\n\n                // solhint-disable-next-line no-inline-assembly\n                assembly {\n                    let returndata_size := mload(returndata)\n                    revert(add(32, returndata), returndata_size)\n                }\n            } else {\n                revert(errorMessage);\n            }\n        }\n    }\n}\n"
      },
      "@openzeppelin/contracts/utils/Context.sol": {
        "content": "// SPDX-License-Identifier: MIT\n\npragma solidity >=0.6.0 <0.8.0;\n\n/*\n * @dev Provides information about the current execution context, including the\n * sender of the transaction and its data. While these are generally available\n * via msg.sender and msg.data, they should not be accessed in such a direct\n * manner, since when dealing with GSN meta-transactions the account sending and\n * paying for execution may not be the actual sender (as far as an application\n * is concerned).\n *\n * This contract is only required for intermediate, library-like contracts.\n */\nabstract contract Context {\n    function _msgSender() internal view virtual returns (address payable) {\n        return msg.sender;\n    }\n\n    function _msgData() internal view virtual returns (bytes memory) {\n        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691\n        return msg.data;\n    }\n}\n"
      },
      "@openzeppelin/contracts/utils/EnumerableSet.sol": {
        "content": "// SPDX-License-Identifier: MIT\n\npragma solidity >=0.6.0 <0.8.0;\n\n/**\n * @dev Library for managing\n * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive\n * types.\n *\n * Sets have the following properties:\n *\n * - Elements are added, removed, and checked for existence in constant time\n * (O(1)).\n * - Elements are enumerated in O(n). No guarantees are made on the ordering.\n *\n * ```\n * contract Example {\n *     // Add the library methods\n *     using EnumerableSet for EnumerableSet.AddressSet;\n *\n *     // Declare a set state variable\n *     EnumerableSet.AddressSet private mySet;\n * }\n * ```\n *\n * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)\n * and `uint256` (`UintSet`) are supported.\n */\nlibrary EnumerableSet {\n    // To implement this library for multiple types with as little code\n    // repetition as possible, we write it in terms of a generic Set type with\n    // bytes32 values.\n    // The Set implementation uses private functions, and user-facing\n    // implementations (such as AddressSet) are just wrappers around the\n    // underlying Set.\n    // This means that we can only create new EnumerableSets for types that fit\n    // in bytes32.\n\n    struct Set {\n        // Storage of set values\n        bytes32[] _values;\n\n        // Position of the value in the `values` array, plus 1 because index 0\n        // means a value is not in the set.\n        mapping (bytes32 => uint256) _indexes;\n    }\n\n    /**\n     * @dev Add a value to a set. O(1).\n     *\n     * Returns true if the value was added to the set, that is if it was not\n     * already present.\n     */\n    function _add(Set storage set, bytes32 value) private returns (bool) {\n        if (!_contains(set, value)) {\n            set._values.push(value);\n            // The value is stored at length-1, but we add 1 to all indexes\n            // and use 0 as a sentinel value\n            set._indexes[value] = set._values.length;\n            return true;\n        } else {\n            return false;\n        }\n    }\n\n    /**\n     * @dev Removes a value from a set. O(1).\n     *\n     * Returns true if the value was removed from the set, that is if it was\n     * present.\n     */\n    function _remove(Set storage set, bytes32 value) private returns (bool) {\n        // We read and store the value's index to prevent multiple reads from the same storage slot\n        uint256 valueIndex = set._indexes[value];\n\n        if (valueIndex != 0) { // Equivalent to contains(set, value)\n            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in\n            // the array, and then remove the last element (sometimes called as 'swap and pop').\n            // This modifies the order of the array, as noted in {at}.\n\n            uint256 toDeleteIndex = valueIndex - 1;\n            uint256 lastIndex = set._values.length - 1;\n\n            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs\n            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.\n\n            bytes32 lastvalue = set._values[lastIndex];\n\n            // Move the last value to the index where the value to delete is\n            set._values[toDeleteIndex] = lastvalue;\n            // Update the index for the moved value\n            set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based\n\n            // Delete the slot where the moved value was stored\n            set._values.pop();\n\n            // Delete the index for the deleted slot\n            delete set._indexes[value];\n\n            return true;\n        } else {\n            return false;\n        }\n    }\n\n    /**\n     * @dev Returns true if the value is in the set. O(1).\n     */\n    function _contains(Set storage set, bytes32 value) private view returns (bool) {\n        return set._indexes[value] != 0;\n    }\n\n    /**\n     * @dev Returns the number of values on the set. O(1).\n     */\n    function _length(Set storage set) private view returns (uint256) {\n        return set._values.length;\n    }\n\n   /**\n    * @dev Returns the value stored at position `index` in the set. O(1).\n    *\n    * Note that there are no guarantees on the ordering of values inside the\n    * array, and it may change when more values are added or removed.\n    *\n    * Requirements:\n    *\n    * - `index` must be strictly less than {length}.\n    */\n    function _at(Set storage set, uint256 index) private view returns (bytes32) {\n        require(set._values.length > index, \"EnumerableSet: index out of bounds\");\n        return set._values[index];\n    }\n\n    // Bytes32Set\n\n    struct Bytes32Set {\n        Set _inner;\n    }\n\n    /**\n     * @dev Add a value to a set. O(1).\n     *\n     * Returns true if the value was added to the set, that is if it was not\n     * already present.\n     */\n    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {\n        return _add(set._inner, value);\n    }\n\n    /**\n     * @dev Removes a value from a set. O(1).\n     *\n     * Returns true if the value was removed from the set, that is if it was\n     * present.\n     */\n    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {\n        return _remove(set._inner, value);\n    }\n\n    /**\n     * @dev Returns true if the value is in the set. O(1).\n     */\n    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {\n        return _contains(set._inner, value);\n    }\n\n    /**\n     * @dev Returns the number of values in the set. O(1).\n     */\n    function length(Bytes32Set storage set) internal view returns (uint256) {\n        return _length(set._inner);\n    }\n\n   /**\n    * @dev Returns the value stored at position `index` in the set. O(1).\n    *\n    * Note that there are no guarantees on the ordering of values inside the\n    * array, and it may change when more values are added or removed.\n    *\n    * Requirements:\n    *\n    * - `index` must be strictly less than {length}.\n    */\n    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {\n        return _at(set._inner, index);\n    }\n\n    // AddressSet\n\n    struct AddressSet {\n        Set _inner;\n    }\n\n    /**\n     * @dev Add a value to a set. O(1).\n     *\n     * Returns true if the value was added to the set, that is if it was not\n     * already present.\n     */\n    function add(AddressSet storage set, address value) internal returns (bool) {\n        return _add(set._inner, bytes32(uint256(uint160(value))));\n    }\n\n    /**\n     * @dev Removes a value from a set. O(1).\n     *\n     * Returns true if the value was removed from the set, that is if it was\n     * present.\n     */\n    function remove(AddressSet storage set, address value) internal returns (bool) {\n        return _remove(set._inner, bytes32(uint256(uint160(value))));\n    }\n\n    /**\n     * @dev Returns true if the value is in the set. O(1).\n     */\n    function contains(AddressSet storage set, address value) internal view returns (bool) {\n        return _contains(set._inner, bytes32(uint256(uint160(value))));\n    }\n\n    /**\n     * @dev Returns the number of values in the set. O(1).\n     */\n    function length(AddressSet storage set) internal view returns (uint256) {\n        return _length(set._inner);\n    }\n\n   /**\n    * @dev Returns the value stored at position `index` in the set. O(1).\n    *\n    * Note that there are no guarantees on the ordering of values inside the\n    * array, and it may change when more values are added or removed.\n    *\n    * Requirements:\n    *\n    * - `index` must be strictly less than {length}.\n    */\n    function at(AddressSet storage set, uint256 index) internal view returns (address) {\n        return address(uint160(uint256(_at(set._inner, index))));\n    }\n\n\n    // UintSet\n\n    struct UintSet {\n        Set _inner;\n    }\n\n    /**\n     * @dev Add a value to a set. O(1).\n     *\n     * Returns true if the value was added to the set, that is if it was not\n     * already present.\n     */\n    function add(UintSet storage set, uint256 value) internal returns (bool) {\n        return _add(set._inner, bytes32(value));\n    }\n\n    /**\n     * @dev Removes a value from a set. O(1).\n     *\n     * Returns true if the value was removed from the set, that is if it was\n     * present.\n     */\n    function remove(UintSet storage set, uint256 value) internal returns (bool) {\n        return _remove(set._inner, bytes32(value));\n    }\n\n    /**\n     * @dev Returns true if the value is in the set. O(1).\n     */\n    function contains(UintSet storage set, uint256 value) internal view returns (bool) {\n        return _contains(set._inner, bytes32(value));\n    }\n\n    /**\n     * @dev Returns the number of values on the set. O(1).\n     */\n    function length(UintSet storage set) internal view returns (uint256) {\n        return _length(set._inner);\n    }\n\n   /**\n    * @dev Returns the value stored at position `index` in the set. O(1).\n    *\n    * Note that there are no guarantees on the ordering of values inside the\n    * array, and it may change when more values are added or removed.\n    *\n    * Requirements:\n    *\n    * - `index` must be strictly less than {length}.\n    */\n    function at(UintSet storage set, uint256 index) internal view returns (uint256) {\n        return uint256(_at(set._inner, index));\n    }\n}\n"
      },
      "contracts/lib/ERC20MaxSupplyPreMine.sol": {
        "content": "// SPDX-License-Identifier: MIT\n\npragma solidity >=0.6.0 <0.8.0;\n\nimport \"@openzeppelin/contracts/utils/Context.sol\";\nimport \"./IERC20MaxSupply.sol\";\nimport \"@openzeppelin/contracts/math/SafeMath.sol\";\n\n/**\n * @dev Implementation of the {IERC20} interface.\n *\n * This implementation is agnostic to the way tokens are created. This means\n * that a supply mechanism has to be added in a derived contract using {_mint}.\n * For a generic mechanism see {ERC20PresetMinterPauser}.\n *\n * TIP: For a detailed writeup see our guide\n * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How\n * to implement supply mechanisms].\n *\n * We have followed general OpenZeppelin guidelines: functions revert instead\n * of returning `false` on failure. This behavior is nonetheless conventional\n * and does not conflict with the expectations of ERC20 applications.\n *\n * Additionally, an {Approval} event is emitted on calls to {transferFrom}.\n * This allows applications to reconstruct the allowance for all accounts just\n * by listening to said events. Other implementations of the EIP may not emit\n * these events, as it isn't required by the specification.\n *\n * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}\n * functions have been added to mitigate the well-known issues around setting\n * allowances. See {IERC20-approve}.\n */\ncontract ERC20MaxSupply is Context, IERC20 {\n    using SafeMath for uint256;\n\n    mapping (address => uint256) private _balances;\n\n    mapping (address => mapping (address => uint256)) private _allowances;\n\n    uint256 private _totalSupply;\n\n    string private _name;\n    string private _symbol;\n    uint8 private _decimals;\n\n    uint256 private constant _maxSupply = 100000000000000000000000000;\n\n    // Copied and modified from YAM code:\n    // https://github.com/yam-finance/yam-protocol/blob/master/contracts/token/YAMGovernanceStorage.sol\n    // https://github.com/yam-finance/yam-protocol/blob/master/contracts/token/YAMGovernance.sol\n    // Which is copied and modified from COMPOUND:\n    // https://github.com/compound-finance/compound-protocol/blob/master/contracts/Governance/Comp.sol\n\n    mapping (address => address) internal _delegates;\n\n    /// @notice A checkpoint for marking number of votes from a given block\n    struct Checkpoint {\n        uint32 fromBlock;\n        uint256 votes;\n    }\n\n    /// @notice A record of votes checkpoints for each account, by index\n    mapping (address => mapping (uint32 => Checkpoint)) public checkpoints;\n\n    /// @notice The number of checkpoints for each account\n    mapping (address => uint32) public numCheckpoints;\n\n    /// @notice The EIP-712 typehash for the contract's domain\n    bytes32 public constant DOMAIN_TYPEHASH = keccak256(\"EIP712Domain(string name,uint256 chainId,address verifyingContract)\");\n\n    /// @notice The EIP-712 typehash for the delegation struct used by the contract\n    bytes32 public constant DELEGATION_TYPEHASH = keccak256(\"Delegation(address delegatee,uint256 nonce,uint256 expiry)\");\n\n    /// @notice A record of states for signing / validating signatures\n    mapping (address => uint) public nonces;\n\n    /// @notice An event thats emitted when an account changes its delegate\n    event DelegateChanged(address indexed delegator, address indexed fromDelegate, address indexed toDelegate);\n\n    /// @notice An event thats emitted when a delegate account's vote balance changes\n    event DelegateVotesChanged(address indexed delegate, uint previousBalance, uint newBalance);\n\n\n    /**\n     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with\n     * a default value of 18.\n     *\n     * To select a different value for {decimals}, use {_setupDecimals}.\n     *\n     * All three of these values are immutable: they can only be set once during\n     * construction.\n     */\n    constructor (string memory name_, string memory symbol_) public {\n        _name = name_;\n        _symbol = symbol_;\n        _decimals = 18;\n    }\n\n    function maxSupply() public override view returns (uint256) {\n        return _maxSupply;\n    }\n\n    /**\n     * @dev Returns the name of the token.\n     */\n    function name() public view virtual returns (string memory) {\n        return _name;\n    }\n\n    /**\n     * @dev Returns the symbol of the token, usually a shorter version of the\n     * name.\n     */\n    function symbol() public view virtual returns (string memory) {\n        return _symbol;\n    }\n\n    /**\n     * @dev Returns the number of decimals used to get its user representation.\n     * For example, if `decimals` equals `2`, a balance of `505` tokens should\n     * be displayed to a user as `5,05` (`505 / 10 ** 2`).\n     *\n     * Tokens usually opt for a value of 18, imitating the relationship between\n     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is\n     * called.\n     *\n     * NOTE: This information is only used for _display_ purposes: it in\n     * no way affects any of the arithmetic of the contract, including\n     * {IERC20-balanceOf} and {IERC20-transfer}.\n     */\n    function decimals() public view virtual returns (uint8) {\n        return _decimals;\n    }\n\n    /**\n     * @dev See {IERC20-totalSupply}.\n     */\n    function totalSupply() public view virtual override returns (uint256) {\n        return _totalSupply;\n    }\n\n    /**\n     * @dev See {IERC20-balanceOf}.\n     */\n    function balanceOf(address account) public view virtual override returns (uint256) {\n        return _balances[account];\n    }\n\n    /**\n     * @dev See {IERC20-transfer}.\n     *\n     * Requirements:\n     *\n     * - `recipient` cannot be the zero address.\n     * - the caller must have a balance of at least `amount`.\n     */\n    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {\n        _transfer(_msgSender(), recipient, amount);\n        return true;\n    }\n\n    /**\n     * @dev See {IERC20-allowance}.\n     */\n    function allowance(address owner, address spender) public view virtual override returns (uint256) {\n        return _allowances[owner][spender];\n    }\n\n    /**\n     * @dev See {IERC20-approve}.\n     *\n     * Requirements:\n     *\n     * - `spender` cannot be the zero address.\n     */\n    function approve(address spender, uint256 amount) public virtual override returns (bool) {\n        _approve(_msgSender(), spender, amount);\n        return true;\n    }\n\n    /**\n     * @dev See {IERC20-transferFrom}.\n     *\n     * Emits an {Approval} event indicating the updated allowance. This is not\n     * required by the EIP. See the note at the beginning of {ERC20}.\n     *\n     * Requirements:\n     *\n     * - `sender` and `recipient` cannot be the zero address.\n     * - `sender` must have a balance of at least `amount`.\n     * - the caller must have allowance for ``sender``'s tokens of at least\n     * `amount`.\n     */\n    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {\n        _transfer(sender, recipient, amount);\n        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, \"ERC20: transfer amount exceeds allowance\"));\n        return true;\n    }\n\n    /**\n     * @dev Atomically increases the allowance granted to `spender` by the caller.\n     *\n     * This is an alternative to {approve} that can be used as a mitigation for\n     * problems described in {IERC20-approve}.\n     *\n     * Emits an {Approval} event indicating the updated allowance.\n     *\n     * Requirements:\n     *\n     * - `spender` cannot be the zero address.\n     */\n    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {\n        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));\n        return true;\n    }\n\n    /**\n     * @dev Atomically decreases the allowance granted to `spender` by the caller.\n     *\n     * This is an alternative to {approve} that can be used as a mitigation for\n     * problems described in {IERC20-approve}.\n     *\n     * Emits an {Approval} event indicating the updated allowance.\n     *\n     * Requirements:\n     *\n     * - `spender` cannot be the zero address.\n     * - `spender` must have allowance for the caller of at least\n     * `subtractedValue`.\n     */\n    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {\n        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, \"ERC20: decreased allowance below zero\"));\n        return true;\n    }\n\n    /**\n     * @dev Moves tokens `amount` from `sender` to `recipient`.\n     *\n     * This is internal function is equivalent to {transfer}, and can be used to\n     * e.g. implement automatic token fees, slashing mechanisms, etc.\n     *\n     * Emits a {Transfer} event.\n     *\n     * Requirements:\n     *\n     * - `sender` cannot be the zero address.\n     * - `recipient` cannot be the zero address.\n     * - `sender` must have a balance of at least `amount`.\n     */\n    function _transfer(address sender, address recipient, uint256 amount) internal virtual {\n        require(sender != address(0), \"ERC20: transfer from the zero address\");\n        require(recipient != address(0), \"ERC20: transfer to the zero address\");\n\n        _beforeTokenTransfer(sender, recipient, amount);\n\n        _balances[sender] = _balances[sender].sub(amount, \"ERC20: transfer amount exceeds balance\");\n        _balances[recipient] = _balances[recipient].add(amount);\n\n        emit Transfer(sender, recipient, amount);\n\n        _moveDelegates(_delegates[sender], _delegates[recipient], amount);\n    }\n\n    /** @dev Creates `amount` tokens and assigns them to `account`, increasing\n     * the total supply.\n     *\n     * Emits a {Transfer} event with `from` set to the zero address.\n     *\n     * Requirements:\n     *\n     * - `to` cannot be the zero address.\n     */\n    function _mint(address account, uint256 amount) internal returns(bool) {\n        require(account != address(0), 'ERC20: mint to the zero address');\n        if (amount.add(_totalSupply) > _maxSupply) {\n            return false;\n        }\n\n        _totalSupply = _totalSupply.add(amount);\n        _balances[account] = _balances[account].add(amount);\n        emit Transfer(address(0), account, amount);\n        return true;\n    }\n\n    /**\n     * @dev Destroys `amount` tokens from `account`, reducing the\n     * total supply.\n     *\n     * Emits a {Transfer} event with `to` set to the zero address.\n     *\n     * Requirements:\n     *\n     * - `account` cannot be the zero address.\n     * - `account` must have at least `amount` tokens.\n     */\n    function _burn(address account, uint256 amount) internal virtual {\n        require(account != address(0), \"ERC20: burn from the zero address\");\n\n        _beforeTokenTransfer(account, address(0), amount);\n\n        _balances[account] = _balances[account].sub(amount, \"ERC20: burn amount exceeds balance\");\n        _totalSupply = _totalSupply.sub(amount);\n        emit Transfer(account, address(0), amount);\n    }\n\n    /**\n     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.\n     *\n     * This internal function is equivalent to `approve`, and can be used to\n     * e.g. set automatic allowances for certain subsystems, etc.\n     *\n     * Emits an {Approval} event.\n     *\n     * Requirements:\n     *\n     * - `owner` cannot be the zero address.\n     * - `spender` cannot be the zero address.\n     */\n    function _approve(address owner, address spender, uint256 amount) internal virtual {\n        require(owner != address(0), \"ERC20: approve from the zero address\");\n        require(spender != address(0), \"ERC20: approve to the zero address\");\n\n        _allowances[owner][spender] = amount;\n        emit Approval(owner, spender, amount);\n    }\n\n    /**\n     * @dev Sets {decimals} to a value other than the default one of 18.\n     *\n     * WARNING: This function should only be called from the constructor. Most\n     * applications that interact with token contracts will not expect\n     * {decimals} to ever change, and may work incorrectly if it does.\n     */\n    function _setupDecimals(uint8 decimals_) internal virtual {\n        _decimals = decimals_;\n    }\n\n    /**\n     * @dev Hook that is called before any transfer of tokens. This includes\n     * minting and burning.\n     *\n     * Calling conditions:\n     *\n     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens\n     * will be to transferred to `to`.\n     * - when `from` is zero, `amount` tokens will be minted for `to`.\n     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.\n     * - `from` and `to` are never both zero.\n     *\n     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].\n     */\n    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }\n\n    /**\n     * @notice Delegate votes from `msg.sender` to `delegatee`\n     * @param delegator The address to get delegatee for\n     */\n    function delegates(address delegator)\n    external\n    view\n    returns (address)\n    {\n        return _delegates[delegator];\n    }\n\n    /**\n     * @notice Delegate votes from `msg.sender` to `delegatee`\n    * @param delegatee The address to delegate votes to\n    */\n    function delegate(address delegatee) external {\n        return _delegate(msg.sender, delegatee);\n    }\n\n    /**\n     * @notice Delegates votes from signatory to `delegatee`\n     * @param delegatee The address to delegate votes to\n     * @param nonce The contract state required to match the signature\n     * @param expiry The time at which to expire the signature\n     * @param v The recovery byte of the signature\n     * @param r Half of the ECDSA signature pair\n     * @param s Half of the ECDSA signature pair\n     */\n    function delegateBySig(\n        address delegatee,\n        uint nonce,\n        uint expiry,\n        uint8 v,\n        bytes32 r,\n        bytes32 s\n    )\n    external\n    {\n        bytes32 domainSeparator = keccak256(\n            abi.encode(\n                DOMAIN_TYPEHASH,\n                keccak256(bytes(name())),\n                getChainId(),\n                address(this)\n            )\n        );\n\n        bytes32 structHash = keccak256(\n            abi.encode(\n                DELEGATION_TYPEHASH,\n                delegatee,\n                nonce,\n                expiry\n            )\n        );\n\n        bytes32 digest = keccak256(\n            abi.encodePacked(\n                \"\\x19\\x01\",\n                domainSeparator,\n                structHash\n            )\n        );\n\n        address signatory = ecrecover(digest, v, r, s);\n        require(signatory != address(0), \"QNS::delegateBySig: invalid signature\");\n        require(nonce == nonces[signatory]++, \"QNS::delegateBySig: invalid nonce\");\n        require(block.timestamp <= expiry, \"QNS::delegateBySig: signature expired\");\n        return _delegate(signatory, delegatee);\n    }\n\n    /**\n     * @notice Gets the current votes balance for `account`\n     * @param account The address to get votes balance\n     * @return The number of current votes for `account`\n     */\n    function getCurrentVotes(address account)\n    external\n    view\n    returns (uint256)\n    {\n        uint32 nCheckpoints = numCheckpoints[account];\n        return nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;\n    }\n\n    /**\n     * @notice Determine the prior number of votes for an account as of a block number\n     * @dev Block number must be a finalized block or else this function will revert to prevent misinformation.\n     * @param account The address of the account to check\n     * @param blockNumber The block number to get the vote balance at\n     * @return The number of votes the account had as of the given block\n     */\n    function getPriorVotes(address account, uint blockNumber)\n    external\n    view\n    returns (uint256)\n    {\n        require(blockNumber < block.number, \"QNS::getPriorVotes: not yet determined\");\n\n        uint32 nCheckpoints = numCheckpoints[account];\n        if (nCheckpoints == 0) {\n            return 0;\n        }\n\n        // First check most recent balance\n        if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {\n            return checkpoints[account][nCheckpoints - 1].votes;\n        }\n\n        // Next check implicit zero balance\n        if (checkpoints[account][0].fromBlock > blockNumber) {\n            return 0;\n        }\n\n        uint32 lower = 0;\n        uint32 upper = nCheckpoints - 1;\n        while (upper > lower) {\n            uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow\n            Checkpoint memory cp = checkpoints[account][center];\n            if (cp.fromBlock == blockNumber) {\n                return cp.votes;\n            } else if (cp.fromBlock < blockNumber) {\n                lower = center;\n            } else {\n                upper = center - 1;\n            }\n        }\n        return checkpoints[account][lower].votes;\n    }\n\n    function _delegate(address delegator, address delegatee)\n    internal\n    {\n        address currentDelegate = _delegates[delegator];\n        uint256 delegatorBalance = balanceOf(delegator); // balance of underlying QNSs (not scaled);\n        _delegates[delegator] = delegatee;\n\n        emit DelegateChanged(delegator, currentDelegate, delegatee);\n\n        _moveDelegates(currentDelegate, delegatee, delegatorBalance);\n    }\n\n    function _moveDelegates(address srcRep, address dstRep, uint256 amount) internal {\n        if (srcRep != dstRep && amount > 0) {\n            if (srcRep != address(0)) {\n                // decrease old representative\n                uint32 srcRepNum = numCheckpoints[srcRep];\n                uint256 srcRepOld = srcRepNum > 0 ? checkpoints[srcRep][srcRepNum - 1].votes : 0;\n                uint256 srcRepNew = srcRepOld.sub(amount);\n                _writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew);\n            }\n\n            if (dstRep != address(0)) {\n                // increase new representative\n                uint32 dstRepNum = numCheckpoints[dstRep];\n                uint256 dstRepOld = dstRepNum > 0 ? checkpoints[dstRep][dstRepNum - 1].votes : 0;\n                uint256 dstRepNew = dstRepOld.add(amount);\n                _writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);\n            }\n        }\n    }\n\n    function _writeCheckpoint(\n        address delegatee,\n        uint32 nCheckpoints,\n        uint256 oldVotes,\n        uint256 newVotes\n    )\n    internal\n    {\n        uint32 blockNumber = safe32(block.number, \"QNS::_writeCheckpoint: block number exceeds 32 bits\");\n\n        if (nCheckpoints > 0 && checkpoints[delegatee][nCheckpoints - 1].fromBlock == blockNumber) {\n            checkpoints[delegatee][nCheckpoints - 1].votes = newVotes;\n        } else {\n            checkpoints[delegatee][nCheckpoints] = Checkpoint(blockNumber, newVotes);\n            numCheckpoints[delegatee] = nCheckpoints + 1;\n        }\n\n        emit DelegateVotesChanged(delegatee, oldVotes, newVotes);\n    }\n\n    function safe32(uint n, string memory errorMessage) internal pure returns (uint32) {\n        require(n < 2**32, errorMessage);\n        return uint32(n);\n    }\n\n    function getChainId() internal pure returns (uint) {\n        uint256 chainId;\n        assembly { chainId := chainid() }\n        return chainId;\n    }\n}\n"
      },
      "contracts/lib/IERC20MaxSupply.sol": {
        "content": "// SPDX-License-Identifier: MIT\n\npragma solidity >=0.6.0 <0.8.0;\n\n/**\n * @dev Interface of the ERC20 standard as defined in the EIP.\n */\ninterface IERC20 {\n\n    function maxSupply() external view returns (uint256);\n\n    /**\n     * @dev Returns the amount of tokens in existence.\n     */\n    function totalSupply() external view returns (uint256);\n\n    /**\n     * @dev Returns the amount of tokens owned by `account`.\n     */\n    function balanceOf(address account) external view returns (uint256);\n\n    /**\n     * @dev Moves `amount` tokens from the caller's account to `recipient`.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * Emits a {Transfer} event.\n     */\n    function transfer(address recipient, uint256 amount) external returns (bool);\n\n    /**\n     * @dev Returns the remaining number of tokens that `spender` will be\n     * allowed to spend on behalf of `owner` through {transferFrom}. This is\n     * zero by default.\n     *\n     * This value changes when {approve} or {transferFrom} are called.\n     */\n    function allowance(address owner, address spender) external view returns (uint256);\n\n    /**\n     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * IMPORTANT: Beware that changing an allowance with this method brings the risk\n     * that someone may use both the old and the new allowance by unfortunate\n     * transaction ordering. One possible solution to mitigate this race\n     * condition is to first reduce the spender's allowance to 0 and set the\n     * desired value afterwards:\n     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729\n     *\n     * Emits an {Approval} event.\n     */\n    function approve(address spender, uint256 amount) external returns (bool);\n\n    /**\n     * @dev Moves `amount` tokens from `sender` to `recipient` using the\n     * allowance mechanism. `amount` is then deducted from the caller's\n     * allowance.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * Emits a {Transfer} event.\n     */\n    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);\n\n    /**\n     * @dev Emitted when `value` tokens are moved from one account (`from`) to\n     * another (`to`).\n     *\n     * Note that `value` may be zero.\n     */\n    event Transfer(address indexed from, address indexed to, uint256 value);\n\n    /**\n     * @dev Emitted when the allowance of a `spender` for an `owner` is set by\n     * a call to {approve}. `value` is the new allowance.\n     */\n    event Approval(address indexed owner, address indexed spender, uint256 value);\n}\n"
      },
      "contracts/lib/SafeERC20.sol": {
        "content": "// SPDX-License-Identifier: MIT\n\npragma solidity >=0.6.0 <0.8.0;\n\nimport \"./IERC20MaxSupply.sol\";\nimport \"@openzeppelin/contracts/math/SafeMath.sol\";\nimport \"@openzeppelin/contracts/utils/Address.sol\";\n\n/**\n * @title SafeERC20\n * @dev Wrappers around ERC20 operations that throw on failure (when the token\n * contract returns false). Tokens that return no value (and instead revert or\n * throw on failure) are also supported, non-reverting calls are assumed to be\n * successful.\n * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,\n * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.\n */\nlibrary SafeERC20 {\n    using SafeMath for uint256;\n    using Address for address;\n\n    function safeTransfer(IERC20 token, address to, uint256 value) internal {\n        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));\n    }\n\n    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {\n        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));\n    }\n\n    /**\n     * @dev Deprecated. This function has issues similar to the ones found in\n     * {IERC20-approve}, and its usage is discouraged.\n     *\n     * Whenever possible, use {safeIncreaseAllowance} and\n     * {safeDecreaseAllowance} instead.\n     */\n    function safeApprove(IERC20 token, address spender, uint256 value) internal {\n        // safeApprove should only be called when setting an initial allowance,\n        // or when resetting it to zero. To increase and decrease it, use\n        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'\n        // solhint-disable-next-line max-line-length\n        require((value == 0) || (token.allowance(address(this), spender) == 0),\n            \"SafeERC20: approve from non-zero to non-zero allowance\"\n        );\n        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));\n    }\n\n    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {\n        uint256 newAllowance = token.allowance(address(this), spender).add(value);\n        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));\n    }\n\n    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {\n        uint256 newAllowance = token.allowance(address(this), spender).sub(value, \"SafeERC20: decreased allowance below zero\");\n        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));\n    }\n\n    /**\n     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement\n     * on the return value: the return value is optional (but if data is returned, it must not be false).\n     * @param token The token targeted by the call.\n     * @param data The call data (encoded using abi.encode or one of its variants).\n     */\n    function _callOptionalReturn(IERC20 token, bytes memory data) private {\n        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since\n        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that\n        // the target address contains contract code and also asserts for success in the low-level call.\n\n        bytes memory returndata = address(token).functionCall(data, \"SafeERC20: low-level call failed\");\n        if (returndata.length > 0) { // Return data is optional\n            // solhint-disable-next-line max-line-length\n            require(abi.decode(returndata, (bool)), \"SafeERC20: ERC20 operation did not succeed\");\n        }\n    }\n}\n"
      },
      "contracts/MasterChef.sol": {
        "content": "pragma solidity 0.6.12;\n\nimport \"./lib/SafeERC20.sol\";\nimport \"@openzeppelin/contracts/utils/EnumerableSet.sol\";\nimport \"@openzeppelin/contracts/math/SafeMath.sol\";\nimport \"@openzeppelin/contracts/access/Ownable.sol\";\nimport \"./QuantoSwapToken.sol\";\nimport \"./lib/IERC20MaxSupply.sol\";\n\ninterface IMigratorChef {\n    function migrate(IERC20 token) external returns (IERC20);\n}\n\ncontract MasterChef is Ownable {\n    using SafeMath for uint256;\n    using SafeERC20 for IERC20;\n\n    struct UserInfo {\n        uint256 amount;\n        uint256 rewardDebt;\n    }\n\n    struct PoolInfo {\n        IERC20 lpToken;\n        uint256 allocPoint;\n        uint256 lastRewardBlock;\n        uint256 accQNSPerShare;\n    }\n\n    QuantoSwapToken public QNS;\n\n    uint256 public devPercent = 375000;\n    address public devaddr;\n    uint256 public blockWithdrawDev;\n    uint256 public depositedQNS;\n\n    uint256 public QNSPerBlock;\n    uint256 public BONUS_MULTIPLIER;\n    IMigratorChef public migrator;\n    PoolInfo[] public poolInfo;\n    mapping(uint256 => mapping(address => UserInfo)) public userInfo;\n    uint256 public totalAllocPoint;\n    uint256 public startBlock;\n\n    event Earned(address indexed user, uint256 indexed pid, uint256 amount);\n    event Deposit(address indexed user, uint256 indexed pid, uint256 amount);\n    event Withdraw(address indexed user, uint256 indexed pid, uint256 amount);\n    event EmergencyWithdraw(\n        address indexed user,\n        uint256 indexed pid,\n        uint256 amount\n    );\n\n    constructor(\n        QuantoSwapToken _QNS,\n        address _devaddr,\n        uint256 _QNSPerBlock,\n        uint256 _startBlock\n    ) public {\n        QNS = _QNS;\n        devaddr = _devaddr;\n        QNSPerBlock = _QNSPerBlock;\n        startBlock = _startBlock;\n        blockWithdrawDev = _startBlock;\n\n        poolInfo.push(PoolInfo({\n            lpToken: _QNS,\n            allocPoint: 2000,\n            lastRewardBlock: startBlock,\n            accQNSPerShare: 0\n        }));\n\n        totalAllocPoint = 2000;\n        BONUS_MULTIPLIER = 1;\n    }\n\n    function updateMultiplier(uint256 multiplierNumber) public onlyOwner {\n        BONUS_MULTIPLIER = multiplierNumber;\n    }\n\n    function poolLength() external view returns (uint256) {\n        return poolInfo.length;\n    }\n\n    function withdrawDevFee() public{\n        require(blockWithdrawDev < block.number, 'wait for new block');\n        uint256 multiplier = getMultiplier(blockWithdrawDev, block.number);\n        uint256 QNSReward = multiplier.mul(QNSPerBlock);\n        QNS.mint(devaddr, QNSReward.mul(devPercent).div(1000000));\n        blockWithdrawDev = block.number;\n    }\n\n    function newDevAddress(address _devaddr) public onlyOwner {\n        devaddr = _devaddr;\n    }\n\n    function newQNSPerBlock(uint256 _QNSPerBlock) public onlyOwner {\n        massUpdatePools();\n        QNSPerBlock = _QNSPerBlock;\n    }\n\n    function checkDuplicate(IERC20 _lpToken) internal {\n        uint256 length = poolInfo.length;\n        for (uint256 pid = 0; pid < length; ++pid){\n            require(poolInfo[pid].lpToken != _lpToken, \"add: existing pool\");\n        }\n    }\n\n    function add( uint256 _allocPoint, IERC20 _lpToken, bool _withUpdate ) public onlyOwner {\n        if (_withUpdate) {\n            massUpdatePools();\n        }\n        checkDuplicate(_lpToken);\n        uint256 lastRewardBlock = block.number > startBlock ? block.number : startBlock;\n        totalAllocPoint = totalAllocPoint.add(_allocPoint);\n        poolInfo.push(\n            PoolInfo({\n                lpToken: _lpToken,\n                allocPoint: _allocPoint,\n                lastRewardBlock: lastRewardBlock,\n                accQNSPerShare: 0\n            })\n        );\n    }\n\n    function set( uint256 _pid, uint256 _allocPoint) public onlyOwner {\n        massUpdatePools();\n        totalAllocPoint = totalAllocPoint.sub(poolInfo[_pid].allocPoint).add(_allocPoint);\n        poolInfo[_pid].allocPoint = _allocPoint;\n    }\n\n    function setMigrator(IMigratorChef _migrator) public onlyOwner {\n        migrator = _migrator;\n    }\n\n    function migrate(uint256 _pid) public {\n        require(address(migrator) != address(0), \"migrate: no migrator\");\n        PoolInfo storage pool = poolInfo[_pid];\n        IERC20 lpToken = pool.lpToken;\n        uint256 bal = lpToken.balanceOf(address(this));\n        lpToken.safeApprove(address(migrator), bal);\n        IERC20 newLpToken = migrator.migrate(lpToken);\n        pool.lpToken = newLpToken;\n    }\n\n    function getMultiplier(uint256 _from, uint256 _to) public view returns (uint256) {\n        return _to.sub(_from).mul(BONUS_MULTIPLIER);\n    }\n\n    function pendingQNS(uint256 _pid, address _user) external view returns (uint256){\n        PoolInfo storage pool = poolInfo[_pid];\n        UserInfo storage user = userInfo[_pid][_user];\n        uint256 accQNSPerShare = pool.accQNSPerShare;\n        uint256 lpSupply = pool.lpToken.balanceOf(address(this));\n        if (_pid == 0){\n            lpSupply = depositedQNS;\n        }\n        if (block.number > pool.lastRewardBlock && lpSupply != 0) {\n            uint256 multiplier = getMultiplier(pool.lastRewardBlock, block.number);\n            uint256 QNSReward = multiplier.mul(QNSPerBlock).mul(pool.allocPoint).div(totalAllocPoint).mul(625).div(1000);\n            accQNSPerShare = accQNSPerShare.add(QNSReward.mul(1e12).div(lpSupply));\n        }\n        return user.amount.mul(accQNSPerShare).div(1e12).sub(user.rewardDebt);\n    }\n\n    function massUpdatePools() public {\n        uint256 length = poolInfo.length;\n        for (uint256 pid = 0; pid < length; ++pid) {\n            updatePool(pid);\n        }\n    }\n\n    function updatePool(uint256 _pid) public {\n        PoolInfo storage pool = poolInfo[_pid];\n        if (block.number <= pool.lastRewardBlock) {\n            return;\n        }\n        uint256 lpSupply = pool.lpToken.balanceOf(address(this));\n        if (_pid == 0){\n            lpSupply = depositedQNS;\n        }\n        if (lpSupply <= 0) {\n            pool.lastRewardBlock = block.number;\n            return;\n        }\n        uint256 multiplier = getMultiplier(pool.lastRewardBlock, block.number);\n        uint256 QNSReward = multiplier.mul(QNSPerBlock).mul(pool.allocPoint).div(totalAllocPoint).mul(625).div(1000);\n        QNS.mint(address(this), QNSReward);\n        pool.accQNSPerShare = pool.accQNSPerShare.add(QNSReward.mul(1e12).div(lpSupply));\n        pool.lastRewardBlock = block.number;\n    }\n\n    function deposit(uint256 _pid, uint256 _amount) public {\n        require (_pid != 0, 'deposit QNS by staking');\n        PoolInfo storage pool = poolInfo[_pid];\n        UserInfo storage user = userInfo[_pid][msg.sender];\n        updatePool(_pid);\n        if (user.amount > 0) {\n            uint256 pending = user.amount.mul(pool.accQNSPerShare).div(1e12).sub(user.rewardDebt);\n            safeQNSTransfer(msg.sender, pending);\n            emit Earned(msg.sender, _pid, pending);\n        }\n        pool.lpToken.safeTransferFrom(address(msg.sender), address(this), _amount);\n        user.amount = user.amount.add(_amount);\n        user.rewardDebt = user.amount.mul(pool.accQNSPerShare).div(1e12);\n        emit Deposit(msg.sender, _pid, _amount);\n    }\n\n    function withdraw(uint256 _pid, uint256 _amount) public {\n        require (_pid != 0, 'withdraw QNS by unstaking');\n        PoolInfo storage pool = poolInfo[_pid];\n        UserInfo storage user = userInfo[_pid][msg.sender];\n        require(user.amount >= _amount, \"withdraw: not good\");\n        updatePool(_pid);\n        uint256 pending = user.amount.mul(pool.accQNSPerShare).div(1e12).sub(user.rewardDebt);\n        safeQNSTransfer(msg.sender, pending);\n        user.amount = user.amount.sub(_amount);\n        user.rewardDebt = user.amount.mul(pool.accQNSPerShare).div(1e12);\n        pool.lpToken.safeTransfer(address(msg.sender), _amount);\n        emit Withdraw(msg.sender, _pid, _amount);\n        emit Earned(msg.sender, _pid, pending);\n    }\n\n    function enterStaking(uint256 _amount) public {\n        PoolInfo storage pool = poolInfo[0];\n        UserInfo storage user = userInfo[0][msg.sender];\n        updatePool(0);\n        if (user.amount > 0) {\n            uint256 pending = user.amount.mul(pool.accQNSPerShare).div(1e12).sub(user.rewardDebt);\n            if(pending > 0) {\n                safeQNSTransfer(msg.sender, pending);\n                emit Earned(msg.sender, 0, pending);\n            }\n        }\n        if(_amount > 0) {\n            pool.lpToken.safeTransferFrom(address(msg.sender), address(this), _amount);\n            user.amount = user.amount.add(_amount);\n            depositedQNS = depositedQNS.add(_amount);\n        }\n        user.rewardDebt = user.amount.mul(pool.accQNSPerShare).div(1e12);\n        emit Deposit(msg.sender, 0, _amount);\n    }\n\n    function leaveStaking(uint256 _amount) public {\n        PoolInfo storage pool = poolInfo[0];\n        UserInfo storage user = userInfo[0][msg.sender];\n        require(user.amount >= _amount, \"withdraw: not good\");\n        updatePool(0);\n        uint256 pending = user.amount.mul(pool.accQNSPerShare).div(1e12).sub(user.rewardDebt);\n        if(pending > 0) {\n            safeQNSTransfer(msg.sender, pending);\n            emit Earned(msg.sender, 0, pending);\n        }\n        if(_amount > 0) {\n            user.amount = user.amount.sub(_amount);\n            pool.lpToken.safeTransfer(address(msg.sender), _amount);\n            depositedQNS = depositedQNS.sub(_amount);\n        }\n        user.rewardDebt = user.amount.mul(pool.accQNSPerShare).div(1e12);\n        emit Withdraw(msg.sender, 0, _amount);\n    }\n\n    function emergencyWithdraw(uint256 _pid) public {\n        PoolInfo storage pool = poolInfo[_pid];\n        UserInfo storage user = userInfo[_pid][msg.sender];\n        uint256 amountToTransfer = user.amount;\n        user.amount = 0;\n        user.rewardDebt = 0;\n        if (_pid == 0){\n            depositedQNS = depositedQNS.sub(amountToTransfer);\n        }\n        pool.lpToken.safeTransfer(address(msg.sender), amountToTransfer);\n        emit EmergencyWithdraw(msg.sender, _pid, amountToTransfer);\n    }\n\n    function safeQNSTransfer(address _to, uint256 _amount) internal {\n        uint256 QNSBal = QNS.balanceOf(address(this));\n        if (_amount > QNSBal) {\n            QNS.transfer(_to, QNSBal);\n        } else {\n            QNS.transfer(_to, _amount);\n        }\n    }\n}\n"
      },
      "contracts/PreMineTimeLock.sol": {
        "content": "pragma solidity ^0.6.0;\n\nlibrary SafeMath {\n    /**\n     * @dev Returns the addition of two unsigned integers, reverting on\n     * overflow.\n     *\n     * Counterpart to Solidity's `+` operator.\n     *\n     * Requirements:\n     *\n     * - Addition cannot overflow.\n     */\n    function add(uint256 a, uint256 b) internal pure returns (uint256) {\n        uint256 c = a + b;\n        require(c >= a, \"SafeMath: addition overflow\");\n\n        return c;\n    }\n\n    /**\n     * @dev Returns the subtraction of two unsigned integers, reverting on\n     * overflow (when the result is negative).\n     *\n     * Counterpart to Solidity's `-` operator.\n     *\n     * Requirements:\n     *\n     * - Subtraction cannot overflow.\n     */\n    function sub(uint256 a, uint256 b) internal pure returns (uint256) {\n        return sub(a, b, \"SafeMath: subtraction overflow\");\n    }\n\n    /**\n     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on\n     * overflow (when the result is negative).\n     *\n     * Counterpart to Solidity's `-` operator.\n     *\n     * Requirements:\n     *\n     * - Subtraction cannot overflow.\n     */\n    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\n        require(b <= a, errorMessage);\n        uint256 c = a - b;\n\n        return c;\n    }\n\n    /**\n     * @dev Returns the multiplication of two unsigned integers, reverting on\n     * overflow.\n     *\n     * Counterpart to Solidity's `*` operator.\n     *\n     * Requirements:\n     *\n     * - Multiplication cannot overflow.\n     */\n    function mul(uint256 a, uint256 b) internal pure returns (uint256) {\n        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the\n        // benefit is lost if 'b' is also tested.\n        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522\n        if (a == 0) {\n            return 0;\n        }\n\n        uint256 c = a * b;\n        require(c / a == b, \"SafeMath: multiplication overflow\");\n\n        return c;\n    }\n\n    /**\n     * @dev Returns the integer division of two unsigned integers. Reverts on\n     * division by zero. The result is rounded towards zero.\n     *\n     * Counterpart to Solidity's `/` operator. Note: this function uses a\n     * `revert` opcode (which leaves remaining gas untouched) while Solidity\n     * uses an invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function div(uint256 a, uint256 b) internal pure returns (uint256) {\n        return div(a, b, \"SafeMath: division by zero\");\n    }\n\n    /**\n     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on\n     * division by zero. The result is rounded towards zero.\n     *\n     * Counterpart to Solidity's `/` operator. Note: this function uses a\n     * `revert` opcode (which leaves remaining gas untouched) while Solidity\n     * uses an invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\n        require(b > 0, errorMessage);\n        uint256 c = a / b;\n        // assert(a == b * c + a % b); // There is no case in which this doesn't hold\n\n        return c;\n    }\n\n    /**\n     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),\n     * Reverts when dividing by zero.\n     *\n     * Counterpart to Solidity's `%` operator. This function uses a `revert`\n     * opcode (which leaves remaining gas untouched) while Solidity uses an\n     * invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function mod(uint256 a, uint256 b) internal pure returns (uint256) {\n        return mod(a, b, \"SafeMath: modulo by zero\");\n    }\n\n    /**\n     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),\n     * Reverts with custom message when dividing by zero.\n     *\n     * Counterpart to Solidity's `%` operator. This function uses a `revert`\n     * opcode (which leaves remaining gas untouched) while Solidity uses an\n     * invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\n        require(b != 0, errorMessage);\n        return a % b;\n    }\n}\ninterface IERC20 {\n    /**\n     * @dev Returns the amount of tokens in existence.\n     */\n    function totalSupply() external view returns (uint256);\n\n    /**\n     * @dev Returns the amount of tokens owned by `account`.\n     */\n    function balanceOf(address account) external view returns (uint256);\n\n    /**\n     * @dev Moves `amount` tokens from the caller's account to `recipient`.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * Emits a {Transfer} event.\n     */\n    function transfer(address recipient, uint256 amount) external returns (bool);\n\n    /**\n     * @dev Returns the remaining number of tokens that `spender` will be\n     * allowed to spend on behalf of `owner` through {transferFrom}. This is\n     * zero by default.\n     *\n     * This value changes when {approve} or {transferFrom} are called.\n     */\n    function allowance(address owner, address spender) external view returns (uint256);\n\n    /**\n     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * IMPORTANT: Beware that changing an allowance with this method brings the risk\n     * that someone may use both the old and the new allowance by unfortunate\n     * transaction ordering. One possible solution to mitigate this race\n     * condition is to first reduce the spender's allowance to 0 and set the\n     * desired value afterwards:\n     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729\n     *\n     * Emits an {Approval} event.\n     */\n    function approve(address spender, uint256 amount) external returns (bool);\n\n    /**\n     * @dev Moves `amount` tokens from `sender` to `recipient` using the\n     * allowance mechanism. `amount` is then deducted from the caller's\n     * allowance.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * Emits a {Transfer} event.\n     */\n    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);\n\n    /**\n     * @dev Emitted when `value` tokens are moved from one account (`from`) to\n     * another (`to`).\n     *\n     * Note that `value` may be zero.\n     */\n    event Transfer(address indexed from, address indexed to, uint256 value);\n\n    /**\n     * @dev Emitted when the allowance of a `spender` for an `owner` is set by\n     * a call to {approve}. `value` is the new allowance.\n     */\n    event Approval(address indexed owner, address indexed spender, uint256 value);\n}\nlibrary Address {\n    /**\n     * @dev Returns true if `account` is a contract.\n     *\n     * [IMPORTANT]\n     * ====\n     * It is unsafe to assume that an address for which this function returns\n     * false is an externally-owned account (EOA) and not a contract.\n     *\n     * Among others, `isContract` will return false for the following\n     * types of addresses:\n     *\n     *  - an externally-owned account\n     *  - a contract in construction\n     *  - an address where a contract will be created\n     *  - an address where a contract lived, but was destroyed\n     * ====\n     */\n    function isContract(address account) internal view returns (bool) {\n        // This method relies on extcodesize, which returns 0 for contracts in\n        // construction, since the code is only stored at the end of the\n        // constructor execution.\n\n        uint256 size;\n        // solhint-disable-next-line no-inline-assembly\n        assembly { size := extcodesize(account) }\n        return size > 0;\n    }\n\n    /**\n     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to\n     * `recipient`, forwarding all available gas and reverting on errors.\n     *\n     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost\n     * of certain opcodes, possibly making contracts go over the 2300 gas limit\n     * imposed by `transfer`, making them unable to receive funds via\n     * `transfer`. {sendValue} removes this limitation.\n     *\n     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].\n     *\n     * IMPORTANT: because control is transferred to `recipient`, care must be\n     * taken to not create reentrancy vulnerabilities. Consider using\n     * {ReentrancyGuard} or the\n     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].\n     */\n    function sendValue(address payable recipient, uint256 amount) internal {\n        require(address(this).balance >= amount, \"Address: insufficient balance\");\n\n        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value\n        (bool success, ) = recipient.call{ value: amount }(\"\");\n        require(success, \"Address: unable to send value, recipient may have reverted\");\n    }\n\n    /**\n     * @dev Performs a Solidity function call using a low level `call`. A\n     * plain`call` is an unsafe replacement for a function call: use this\n     * function instead.\n     *\n     * If `target` reverts with a revert reason, it is bubbled up by this\n     * function (like regular Solidity function calls).\n     *\n     * Returns the raw returned data. To convert to the expected return value,\n     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].\n     *\n     * Requirements:\n     *\n     * - `target` must be a contract.\n     * - calling `target` with `data` must not revert.\n     *\n     * _Available since v3.1._\n     */\n    function functionCall(address target, bytes memory data) internal returns (bytes memory) {\n        return functionCall(target, data, \"Address: low-level call failed\");\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with\n     * `errorMessage` as a fallback revert reason when `target` reverts.\n     *\n     * _Available since v3.1._\n     */\n    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {\n        return functionCallWithValue(target, data, 0, errorMessage);\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n     * but also transferring `value` wei to `target`.\n     *\n     * Requirements:\n     *\n     * - the calling contract must have an ETH balance of at least `value`.\n     * - the called Solidity function must be `payable`.\n     *\n     * _Available since v3.1._\n     */\n    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {\n        return functionCallWithValue(target, data, value, \"Address: low-level call with value failed\");\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but\n     * with `errorMessage` as a fallback revert reason when `target` reverts.\n     *\n     * _Available since v3.1._\n     */\n    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {\n        require(address(this).balance >= value, \"Address: insufficient balance for call\");\n        require(isContract(target), \"Address: call to non-contract\");\n\n        // solhint-disable-next-line avoid-low-level-calls\n        (bool success, bytes memory returndata) = target.call{ value: value }(data);\n        return _verifyCallResult(success, returndata, errorMessage);\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n     * but performing a static call.\n     *\n     * _Available since v3.3._\n     */\n    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {\n        return functionStaticCall(target, data, \"Address: low-level static call failed\");\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],\n     * but performing a static call.\n     *\n     * _Available since v3.3._\n     */\n    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {\n        require(isContract(target), \"Address: static call to non-contract\");\n\n        // solhint-disable-next-line avoid-low-level-calls\n        (bool success, bytes memory returndata) = target.staticcall(data);\n        return _verifyCallResult(success, returndata, errorMessage);\n    }\n\n    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {\n        if (success) {\n            return returndata;\n        } else {\n            // Look for revert reason and bubble it up if present\n            if (returndata.length > 0) {\n                // The easiest way to bubble the revert reason is using memory via assembly\n\n                // solhint-disable-next-line no-inline-assembly\n                assembly {\n                    let returndata_size := mload(returndata)\n                    revert(add(32, returndata), returndata_size)\n                }\n            } else {\n                revert(errorMessage);\n            }\n        }\n    }\n}\nlibrary SafeERC20 {\n    using SafeMath for uint256;\n    using Address for address;\n\n    function safeTransfer(IERC20 token, address to, uint256 value) internal {\n        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));\n    }\n\n    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {\n        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));\n    }\n\n    /**\n     * @dev Deprecated. This function has issues similar to the ones found in\n     * {IERC20-approve}, and its usage is discouraged.\n     *\n     * Whenever possible, use {safeIncreaseAllowance} and\n     * {safeDecreaseAllowance} instead.\n     */\n    function safeApprove(IERC20 token, address spender, uint256 value) internal {\n        // safeApprove should only be called when setting an initial allowance,\n        // or when resetting it to zero. To increase and decrease it, use\n        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'\n        // solhint-disable-next-line max-line-length\n        require((value == 0) || (token.allowance(address(this), spender) == 0),\n            \"SafeERC20: approve from non-zero to non-zero allowance\"\n        );\n        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));\n    }\n\n    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {\n        uint256 newAllowance = token.allowance(address(this), spender).add(value);\n        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));\n    }\n\n    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {\n        uint256 newAllowance = token.allowance(address(this), spender).sub(value, \"SafeERC20: decreased allowance below zero\");\n        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));\n    }\n\n    /**\n     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement\n     * on the return value: the return value is optional (but if data is returned, it must not be false).\n     * @param token The token targeted by the call.\n     * @param data The call data (encoded using abi.encode or one of its variants).\n     */\n    function _callOptionalReturn(IERC20 token, bytes memory data) private {\n        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since\n        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that\n        // the target address contains contract code and also asserts for success in the low-level call.\n\n        bytes memory returndata = address(token).functionCall(data, \"SafeERC20: low-level call failed\");\n        if (returndata.length > 0) { // Return data is optional\n            // solhint-disable-next-line max-line-length\n            require(abi.decode(returndata, (bool)), \"SafeERC20: ERC20 operation did not succeed\");\n        }\n    }\n}\n\ncontract PreMineTimeLock {\n    using SafeMath for uint;\n    using SafeERC20 for IERC20;\n\n    IERC20 public token;\n    uint constant  public PERIOD = 30 days;\n    uint constant  public CYCLE_TIMES = 10;\n    uint public fixedQuantity;\n    uint public startTime;\n    uint public delay;\n    uint public cycle;\n    uint public hasReward;\n    address public beneficiary;\n    string public introduce;\n\n    event Withdraw(address indexed operator, address indexed to, uint amount);\n\n    constructor(\n        address _beneficiary,\n        address _token,\n        uint _fixedQuantity,\n        uint _startTime,\n        uint _delay,\n        string memory _introduce\n    ) public {\n        require(_beneficiary != address(0) && _token != address(0), \"TimeLock: zero address\");\n        require(_fixedQuantity > 0, \"TimeLock: fixedQuantity is zero\");\n        beneficiary = _beneficiary;\n        token = IERC20(_token);\n        fixedQuantity = _fixedQuantity;\n        delay = _delay;\n        startTime = _startTime.add(_delay);\n        introduce = _introduce;\n    }\n\n\n    function getBalance() public view returns (uint) {\n        return token.balanceOf(address(this));\n    }\n\n    function getReward() public view returns (uint) {\n        if (cycle >= CYCLE_TIMES || block.timestamp <= startTime) {\n            return 0;\n        }\n        uint pCycle = (block.timestamp.sub(startTime)).div(PERIOD);\n        if (pCycle >= CYCLE_TIMES) {\n            return token.balanceOf(address(this));\n        }\n        return pCycle.sub(cycle).mul(fixedQuantity);\n    }\n\n    function withdraw() external {\n        uint reward = getReward();\n        require(reward > 0, \"TimeLock: no reward\");\n        uint pCycle = (block.timestamp.sub(startTime)).div(PERIOD);\n        cycle = pCycle >= CYCLE_TIMES ? CYCLE_TIMES : pCycle;\n        hasReward = hasReward.add(reward);\n        token.safeTransfer(beneficiary, reward);\n        emit Withdraw(msg.sender, beneficiary, reward);\n    }\n\n    function setBeneficiary(address _newBeneficiary) public {\n        require(msg.sender == beneficiary, \"Not beneficiary\");\n        beneficiary = _newBeneficiary;\n    }\n}"
      },
      "contracts/QuantoSwapToken.sol": {
        "content": "pragma solidity 0.6.12;\n\nimport \"./lib/ERC20MaxSupplyPreMine.sol\";\nimport \"@openzeppelin/contracts/access/Ownable.sol\";\n\n\ncontract QuantoSwapToken is ERC20MaxSupply('QuantoSwap Token', 'QNS'), Ownable {\n\n    uint256 private constant _preMined = 150000000000000000000000;\n\n    constructor (address _preMineReceiver) public {\n        QuantoSwapToken.mint(_preMineReceiver, _preMined);\n    }\n\n    /// @notice Creates `_amount` token to `_to`. Must only be called by the owner (MasterChef).\n    function mint(address _to, uint256 _amount) public onlyOwner {\n        _mint(_to, _amount);\n        _moveDelegates(address(0), _delegates[_to], _amount);\n    }\n}"
      },
      "contracts/SmartChef.sol": {
        "content": "pragma solidity 0.6.12;\n\nlibrary SafeMath {\n    /**\n     * @dev Returns the addition of two unsigned integers, reverting on\n     * overflow.\n     *\n     * Counterpart to Solidity's `+` operator.\n     *\n     * Requirements:\n     *\n     * - Addition cannot overflow.\n     */\n    function add(uint256 a, uint256 b) internal pure returns (uint256) {\n        uint256 c = a + b;\n        require(c >= a, 'SafeMath: addition overflow');\n\n        return c;\n    }\n\n    /**\n     * @dev Returns the subtraction of two unsigned integers, reverting on\n     * overflow (when the result is negative).\n     *\n     * Counterpart to Solidity's `-` operator.\n     *\n     * Requirements:\n     *\n     * - Subtraction cannot overflow.\n     */\n    function sub(uint256 a, uint256 b) internal pure returns (uint256) {\n        return sub(a, b, 'SafeMath: subtraction overflow');\n    }\n\n    /**\n     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on\n     * overflow (when the result is negative).\n     *\n     * Counterpart to Solidity's `-` operator.\n     *\n     * Requirements:\n     *\n     * - Subtraction cannot overflow.\n     */\n    function sub(\n        uint256 a,\n        uint256 b,\n        string memory errorMessage\n    ) internal pure returns (uint256) {\n        require(b <= a, errorMessage);\n        uint256 c = a - b;\n\n        return c;\n    }\n\n    /**\n     * @dev Returns the multiplication of two unsigned integers, reverting on\n     * overflow.\n     *\n     * Counterpart to Solidity's `*` operator.\n     *\n     * Requirements:\n     *\n     * - Multiplication cannot overflow.\n     */\n    function mul(uint256 a, uint256 b) internal pure returns (uint256) {\n        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the\n        // benefit is lost if 'b' is also tested.\n        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522\n        if (a == 0) {\n            return 0;\n        }\n\n        uint256 c = a * b;\n        require(c / a == b, 'SafeMath: multiplication overflow');\n\n        return c;\n    }\n\n    /**\n     * @dev Returns the integer division of two unsigned integers. Reverts on\n     * division by zero. The result is rounded towards zero.\n     *\n     * Counterpart to Solidity's `/` operator. Note: this function uses a\n     * `revert` opcode (which leaves remaining gas untouched) while Solidity\n     * uses an invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function div(uint256 a, uint256 b) internal pure returns (uint256) {\n        return div(a, b, 'SafeMath: division by zero');\n    }\n\n    /**\n     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on\n     * division by zero. The result is rounded towards zero.\n     *\n     * Counterpart to Solidity's `/` operator. Note: this function uses a\n     * `revert` opcode (which leaves remaining gas untouched) while Solidity\n     * uses an invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function div(\n        uint256 a,\n        uint256 b,\n        string memory errorMessage\n    ) internal pure returns (uint256) {\n        require(b > 0, errorMessage);\n        uint256 c = a / b;\n        // assert(a == b * c + a % b); // There is no case in which this doesn't hold\n\n        return c;\n    }\n\n    /**\n     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),\n     * Reverts when dividing by zero.\n     *\n     * Counterpart to Solidity's `%` operator. This function uses a `revert`\n     * opcode (which leaves remaining gas untouched) while Solidity uses an\n     * invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function mod(uint256 a, uint256 b) internal pure returns (uint256) {\n        return mod(a, b, 'SafeMath: modulo by zero');\n    }\n\n    /**\n     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),\n     * Reverts with custom message when dividing by zero.\n     *\n     * Counterpart to Solidity's `%` operator. This function uses a `revert`\n     * opcode (which leaves remaining gas untouched) while Solidity uses an\n     * invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function mod(\n        uint256 a,\n        uint256 b,\n        string memory errorMessage\n    ) internal pure returns (uint256) {\n        require(b != 0, errorMessage);\n        return a % b;\n    }\n\n    function min(uint256 x, uint256 y) internal pure returns (uint256 z) {\n        z = x < y ? x : y;\n    }\n\n    // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)\n    function sqrt(uint256 y) internal pure returns (uint256 z) {\n        if (y > 3) {\n            z = y;\n            uint256 x = y / 2 + 1;\n            while (x < z) {\n                z = x;\n                x = (y / x + x) / 2;\n            }\n        } else if (y != 0) {\n            z = 1;\n        }\n    }\n}\ninterface IERC20 {\n    /**\n     * @dev Returns the amount of tokens in existence.\n     */\n    function totalSupply() external view returns (uint256);\n\n    /**\n     * @dev Returns the token decimals.\n     */\n    function decimals() external view returns (uint8);\n\n    /**\n     * @dev Returns the token symbol.\n     */\n    function symbol() external view returns (string memory);\n\n    /**\n     * @dev Returns the token name.\n     */\n    function name() external view returns (string memory);\n\n    /**\n     * @dev Returns the bep token owner.\n     */\n    function getOwner() external view returns (address);\n\n    /**\n     * @dev Returns the amount of tokens owned by `account`.\n     */\n    function balanceOf(address account) external view returns (uint256);\n\n    /**\n     * @dev Moves `amount` tokens from the caller's account to `recipient`.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * Emits a {Transfer} event.\n     */\n    function transfer(address recipient, uint256 amount) external returns (bool);\n\n    /**\n     * @dev Returns the remaining number of tokens that `spender` will be\n     * allowed to spend on behalf of `owner` through {transferFrom}. This is\n     * zero by default.\n     *\n     * This value changes when {approve} or {transferFrom} are called.\n     */\n    function allowance(address _owner, address spender) external view returns (uint256);\n\n    /**\n     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * IMPORTANT: Beware that changing an allowance with this method brings the risk\n     * that someone may use both the old and the new allowance by unfortunate\n     * transaction ordering. One possible solution to mitigate this race\n     * condition is to first reduce the spender's allowance to 0 and set the\n     * desired value afterwards:\n     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729\n     *\n     * Emits an {Approval} event.\n     */\n    function approve(address spender, uint256 amount) external returns (bool);\n\n    /**\n     * @dev Moves `amount` tokens from `sender` to `recipient` using the\n     * allowance mechanism. `amount` is then deducted from the caller's\n     * allowance.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * Emits a {Transfer} event.\n     */\n    function transferFrom(\n        address sender,\n        address recipient,\n        uint256 amount\n    ) external returns (bool);\n\n    /**\n     * @dev Emitted when `value` tokens are moved from one account (`from`) to\n     * another (`to`).\n     *\n     * Note that `value` may be zero.\n     */\n    event Transfer(address indexed from, address indexed to, uint256 value);\n\n    /**\n     * @dev Emitted when the allowance of a `spender` for an `owner` is set by\n     * a call to {approve}. `value` is the new allowance.\n     */\n    event Approval(address indexed owner, address indexed spender, uint256 value);\n}\nlibrary Address {\n    /**\n     * @dev Returns true if `account` is a contract.\n     *\n     * [IMPORTANT]\n     * ====\n     * It is unsafe to assume that an address for which this function returns\n     * false is an externally-owned account (EOA) and not a contract.\n     *\n     * Among others, `isContract` will return false for the following\n     * types of addresses:\n     *\n     *  - an externally-owned account\n     *  - a contract in construction\n     *  - an address where a contract will be created\n     *  - an address where a contract lived, but was destroyed\n     * ====\n     */\n    function isContract(address account) internal view returns (bool) {\n        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts\n        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned\n        // for accounts without code, i.e. `keccak256('')`\n        bytes32 codehash;\n        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;\n        // solhint-disable-next-line no-inline-assembly\n        assembly {\n            codehash := extcodehash(account)\n        }\n        return (codehash != accountHash && codehash != 0x0);\n    }\n\n    /**\n     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to\n     * `recipient`, forwarding all available gas and reverting on errors.\n     *\n     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost\n     * of certain opcodes, possibly making contracts go over the 2300 gas limit\n     * imposed by `transfer`, making them unable to receive funds via\n     * `transfer`. {sendValue} removes this limitation.\n     *\n     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].\n     *\n     * IMPORTANT: because control is transferred to `recipient`, care must be\n     * taken to not create reentrancy vulnerabilities. Consider using\n     * {ReentrancyGuard} or the\n     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].\n     */\n    function sendValue(address payable recipient, uint256 amount) internal {\n        require(address(this).balance >= amount, 'Address: insufficient balance');\n\n        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value\n        (bool success, ) = recipient.call{value: amount}('');\n        require(success, 'Address: unable to send value, recipient may have reverted');\n    }\n\n    /**\n     * @dev Performs a Solidity function call using a low level `call`. A\n     * plain`call` is an unsafe replacement for a function call: use this\n     * function instead.\n     *\n     * If `target` reverts with a revert reason, it is bubbled up by this\n     * function (like regular Solidity function calls).\n     *\n     * Returns the raw returned data. To convert to the expected return value,\n     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].\n     *\n     * Requirements:\n     *\n     * - `target` must be a contract.\n     * - calling `target` with `data` must not revert.\n     *\n     * _Available since v3.1._\n     */\n    function functionCall(address target, bytes memory data) internal returns (bytes memory) {\n        return functionCall(target, data, 'Address: low-level call failed');\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with\n     * `errorMessage` as a fallback revert reason when `target` reverts.\n     *\n     * _Available since v3.1._\n     */\n    function functionCall(\n        address target,\n        bytes memory data,\n        string memory errorMessage\n    ) internal returns (bytes memory) {\n        return _functionCallWithValue(target, data, 0, errorMessage);\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n     * but also transferring `value` wei to `target`.\n     *\n     * Requirements:\n     *\n     * - the calling contract must have an ETH balance of at least `value`.\n     * - the called Solidity function must be `payable`.\n     *\n     * _Available since v3.1._\n     */\n    function functionCallWithValue(\n        address target,\n        bytes memory data,\n        uint256 value\n    ) internal returns (bytes memory) {\n        return functionCallWithValue(target, data, value, 'Address: low-level call with value failed');\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but\n     * with `errorMessage` as a fallback revert reason when `target` reverts.\n     *\n     * _Available since v3.1._\n     */\n    function functionCallWithValue(\n        address target,\n        bytes memory data,\n        uint256 value,\n        string memory errorMessage\n    ) internal returns (bytes memory) {\n        require(address(this).balance >= value, 'Address: insufficient balance for call');\n        return _functionCallWithValue(target, data, value, errorMessage);\n    }\n\n    function _functionCallWithValue(\n        address target,\n        bytes memory data,\n        uint256 weiValue,\n        string memory errorMessage\n    ) private returns (bytes memory) {\n        require(isContract(target), 'Address: call to non-contract');\n\n        // solhint-disable-next-line avoid-low-level-calls\n        (bool success, bytes memory returndata) = target.call{value: weiValue}(data);\n        if (success) {\n            return returndata;\n        } else {\n            // Look for revert reason and bubble it up if present\n            if (returndata.length > 0) {\n                // The easiest way to bubble the revert reason is using memory via assembly\n\n                // solhint-disable-next-line no-inline-assembly\n                assembly {\n                    let returndata_size := mload(returndata)\n                    revert(add(32, returndata), returndata_size)\n                }\n            } else {\n                revert(errorMessage);\n            }\n        }\n    }\n}\nlibrary SafeBEP20 {\n    using SafeMath for uint256;\n    using Address for address;\n\n    function safeTransfer(\n        IERC20 token,\n        address to,\n        uint256 value\n    ) internal {\n        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));\n    }\n\n    function safeTransferFrom(\n        IERC20 token,\n        address from,\n        address to,\n        uint256 value\n    ) internal {\n        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));\n    }\n\n    /**\n     * @dev Deprecated. This function has issues similar to the ones found in\n     * {IERC20-approve}, and its usage is discouraged.\n     *\n     * Whenever possible, use {safeIncreaseAllowance} and\n     * {safeDecreaseAllowance} instead.\n     */\n    function safeApprove(\n        IERC20 token,\n        address spender,\n        uint256 value\n    ) internal {\n        // safeApprove should only be called when setting an initial allowance,\n        // or when resetting it to zero. To increase and decrease it, use\n        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'\n        // solhint-disable-next-line max-line-length\n        require(\n            (value == 0) || (token.allowance(address(this), spender) == 0),\n            'SafeBEP20: approve from non-zero to non-zero allowance'\n        );\n        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));\n    }\n\n    function safeIncreaseAllowance(\n        IERC20 token,\n        address spender,\n        uint256 value\n    ) internal {\n        uint256 newAllowance = token.allowance(address(this), spender).add(value);\n        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));\n    }\n\n    function safeDecreaseAllowance(\n        IERC20 token,\n        address spender,\n        uint256 value\n    ) internal {\n        uint256 newAllowance = token.allowance(address(this), spender).sub(\n            value,\n            'SafeBEP20: decreased allowance below zero'\n        );\n        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));\n    }\n\n    /**\n     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement\n     * on the return value: the return value is optional (but if data is returned, it must not be false).\n     * @param token The token targeted by the call.\n     * @param data The call data (encoded using abi.encode or one of its variants).\n     */\n    function _callOptionalReturn(IERC20 token, bytes memory data) private {\n        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since\n        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that\n        // the target address contains contract code and also asserts for success in the low-level call.\n\n        bytes memory returndata = address(token).functionCall(data, 'SafeBEP20: low-level call failed');\n        if (returndata.length > 0) {\n            // Return data is optional\n            // solhint-disable-next-line max-line-length\n            require(abi.decode(returndata, (bool)), 'SafeBEP20: BEP20 operation did not succeed');\n        }\n    }\n}\ncontract Context {\n    // Empty internal constructor, to prevent people from mistakenly deploying\n    // an instance of this contract, which should be used via inheritance.\n    constructor() internal {}\n\n    function _msgSender() internal view returns (address payable) {\n        return msg.sender;\n    }\n\n    function _msgData() internal view returns (bytes memory) {\n        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691\n        return msg.data;\n    }\n}\ncontract Ownable is Context {\n    address private _owner;\n\n    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);\n\n    /**\n     * @dev Initializes the contract setting the deployer as the initial owner.\n     */\n    constructor() internal {\n        address msgSender = _msgSender();\n        _owner = msgSender;\n        emit OwnershipTransferred(address(0), msgSender);\n    }\n\n    /**\n     * @dev Returns the address of the current owner.\n     */\n    function owner() public view returns (address) {\n        return _owner;\n    }\n\n    /**\n     * @dev Throws if called by any account other than the owner.\n     */\n    modifier onlyOwner() {\n        require(_owner == _msgSender(), 'Ownable: caller is not the owner');\n        _;\n    }\n\n    /**\n     * @dev Leaves the contract without owner. It will not be possible to call\n     * `onlyOwner` functions anymore. Can only be called by the current owner.\n     *\n     * NOTE: Renouncing ownership will leave the contract without an owner,\n     * thereby removing any functionality that is only available to the owner.\n     */\n    function renounceOwnership() public onlyOwner {\n        emit OwnershipTransferred(_owner, address(0));\n        _owner = address(0);\n    }\n\n    /**\n     * @dev Transfers ownership of the contract to a new account (`newOwner`).\n     * Can only be called by the current owner.\n     */\n    function transferOwnership(address newOwner) public onlyOwner {\n        _transferOwnership(newOwner);\n    }\n\n    /**\n     * @dev Transfers ownership of the contract to a new account (`newOwner`).\n     */\n    function _transferOwnership(address newOwner) internal {\n        require(newOwner != address(0), 'Ownable: new owner is the zero address');\n        emit OwnershipTransferred(_owner, newOwner);\n        _owner = newOwner;\n    }\n}\n\ncontract SmartChef is Ownable {\n    using SafeMath for uint256;\n    using SafeBEP20 for IERC20;\n\n    // Info of each user.\n    struct UserInfo {\n        uint256 amount;     // How many LP tokens the user has provided.\n        uint256 rewardDebt; // Reward debt. See explanation below.\n    }\n\n    // Info of each pool.\n    struct PoolInfo {\n        IERC20 lpToken;           // Address of LP token contract.\n        uint256 allocPoint;       // How many allocation points assigned to this pool. QNSs to distribute per block.\n        uint256 lastRewardBlock;  // Last block number that QNSs distribution occurs.\n        uint256 accQNSPerShare;  // Accumulated QNSs per share, times PRECISION_FACTOR. See below.\n    }\n\n    IERC20 public stakingToken;\n    IERC20 public rewardToken;\n    uint256 public rewardPerBlock;\n\n    // Info of each pool.\n    PoolInfo[] public poolInfo;\n    // Info of each user that stakes LP tokens.\n    mapping (address => UserInfo) public userInfo;\n    // Total allocation points. Must be the sum of all allocation points in all pools.\n    uint256 public totalAllocPoint = 0;\n    // The block number when QNS mining starts.\n    uint256 public startBlock;\n    // The block number when QNS mining ends.\n    uint256 public bonusEndBlock;\n    // limit 100 QNS\n    uint256 public limitAmount = 1000000000000000000000;\n\n    // The precision factor\n    uint256 public PRECISION_FACTOR;\n\n    event Deposit(address indexed user, uint256 amount);\n    event Withdraw(address indexed user, uint256 amount);\n    event EmergencyWithdraw(address indexed user, uint256 amount);\n    event RefPercentChanged(uint256 currentPercent);\n\n    constructor(\n        IERC20 _stakingToken,\n        IERC20 _rewardToken,\n        uint256 _rewardPerBlock,\n        uint256 _startBlock,\n        uint256 _bonusEndBlock,\n        uint256 _limitStakeToken\n    ) public {\n        stakingToken = _stakingToken;\n        rewardToken = _rewardToken;\n        rewardPerBlock = _rewardPerBlock;\n        startBlock = _startBlock;\n        bonusEndBlock = _bonusEndBlock;\n        limitAmount = _limitStakeToken;\n\n\n        uint256 decimalsRewardToken = uint256(rewardToken.decimals());\n        require(decimalsRewardToken < 30, \"Must be inferior to 30\");\n\n        PRECISION_FACTOR = uint256(10**(uint256(30).sub(decimalsRewardToken)));\n\n        poolInfo.push(PoolInfo({\n            lpToken: _stakingToken,\n            allocPoint: 1000,\n            lastRewardBlock: startBlock,\n            accQNSPerShare: 0\n        }));\n        totalAllocPoint = 1000;\n    }\n\n    function setLimitAmount(uint256 _amount) public onlyOwner {\n        limitAmount = _amount;\n    }\n\n    function remainingLimitAmount(address userAddress) public view returns(uint256) {\n        if (userInfo[userAddress].amount >= limitAmount){\n            return 0;\n        }\n        return limitAmount.sub(userInfo[userAddress].amount);\n    }\n\n    function getMultiplier(uint256 _from, uint256 _to) public view returns (uint256) {\n        if (_to <= bonusEndBlock) {\n            return _to.sub(_from);\n        } else if (_from >= bonusEndBlock) {\n            return 0;\n        } else {\n            return bonusEndBlock.sub(_from);\n        }\n    }\n\n    function pendingReward(address _user) external view returns (uint256) {\n        PoolInfo storage pool = poolInfo[0];\n        UserInfo storage user = userInfo[_user];\n        uint256 accQNSPerShare = pool.accQNSPerShare;\n        uint256 lpSupply = pool.lpToken.balanceOf(address(this));\n        if (block.number > pool.lastRewardBlock && lpSupply != 0) {\n            uint256 multiplier = getMultiplier(pool.lastRewardBlock, block.number);\n            uint256 QNSReward = multiplier.mul(rewardPerBlock).mul(pool.allocPoint).div(totalAllocPoint);\n            accQNSPerShare = accQNSPerShare.add(QNSReward.mul(PRECISION_FACTOR).div(lpSupply));\n        }\n        return user.amount.mul(accQNSPerShare).div(PRECISION_FACTOR).sub(user.rewardDebt);\n    }\n\n    function updatePool(uint256 _pid) public {\n        PoolInfo storage pool = poolInfo[_pid];\n        if (block.number <= pool.lastRewardBlock) {\n            return;\n        }\n        uint256 lpSupply = pool.lpToken.balanceOf(address(this));\n        if (lpSupply == 0) {\n            pool.lastRewardBlock = block.number;\n            return;\n        }\n        uint256 multiplier = getMultiplier(pool.lastRewardBlock, block.number);\n        uint256 QNSReward = multiplier.mul(rewardPerBlock).mul(pool.allocPoint).div(totalAllocPoint);\n        pool.accQNSPerShare = pool.accQNSPerShare.add(QNSReward.mul(PRECISION_FACTOR).div(lpSupply));\n        pool.lastRewardBlock = block.number;\n    }\n\n    function massUpdatePools() public {\n        uint256 length = poolInfo.length;\n        for (uint256 pid = 0; pid < length; ++pid) {\n            updatePool(pid);\n        }\n    }\n\n    function deposit(uint256 _amount) public {\n        PoolInfo storage pool = poolInfo[0];\n        UserInfo storage user = userInfo[msg.sender];\n\n        require(user.amount.add(_amount) <= limitAmount, 'Limit amount');\n\n        updatePool(0);\n        if (user.amount > 0) {\n            uint256 pending = user.amount.mul(pool.accQNSPerShare).div(PRECISION_FACTOR).sub(user.rewardDebt);\n            if(pending > 0) {\n                rewardToken.safeTransfer(address(msg.sender), pending);\n            }\n        }\n        if(_amount > 0) {\n            pool.lpToken.safeTransferFrom(address(msg.sender), address(this), _amount);\n            user.amount = user.amount.add(_amount);\n        }\n        user.rewardDebt = user.amount.mul(pool.accQNSPerShare).div(PRECISION_FACTOR);\n\n\n        emit Deposit(msg.sender, _amount);\n    }\n\n    function withdraw(uint256 _amount) public {\n        PoolInfo storage pool = poolInfo[0];\n        UserInfo storage user = userInfo[msg.sender];\n        require(user.amount >= _amount, \"withdraw: not good\");\n        updatePool(0);\n        uint256 pending = user.amount.mul(pool.accQNSPerShare).div(PRECISION_FACTOR).sub(user.rewardDebt);\n        if(pending > 0) {\n            rewardToken.safeTransfer(address(msg.sender), pending);\n        }\n        if(_amount > 0) {\n            user.amount = user.amount.sub(_amount);\n            user.rewardDebt = user.amount.mul(pool.accQNSPerShare).div(PRECISION_FACTOR);\n            pool.lpToken.safeTransfer(address(msg.sender), _amount);\n        }\n\n        emit Withdraw(msg.sender, _amount);\n    }\n\n    function emergencyWithdraw() public {\n        PoolInfo storage pool = poolInfo[0];\n        UserInfo storage user = userInfo[msg.sender];\n        uint256 amountToTransfer = user.amount;\n        user.amount = 0;\n        user.rewardDebt = 0;\n        if (amountToTransfer > 0){\n            pool.lpToken.safeTransfer(address(msg.sender), amountToTransfer);\n        }\n        emit EmergencyWithdraw(msg.sender, amountToTransfer);\n    }\n\n    function emergencyRewardWithdraw(uint256 _amount) public onlyOwner {\n        require(_amount <= rewardToken.balanceOf(address(this)), 'not enough token');\n        rewardToken.safeTransfer(address(msg.sender), _amount);\n    }\n\n}"
      }
    },
    "settings": {
      "optimizer": {
        "enabled": false,
        "runs": 200
      },
      "outputSelection": {
        "*": {
          "*": [
            "evm.bytecode",
            "evm.deployedBytecode",
            "abi"
          ]
        }
      }
    }
  }}