Blockchain, Cryptography, Bitcoin, Ethereum, Cryptocurrency.
x, even if you had a super computer. There is no known algorithm for determining x, so your only option is to keep adding P to itself until you get X or keep subtracting P from X until you get P. On average, x will be somewhere between 0 and 2²⁵⁶-1, about 2¹²⁸. Thus, it will take you on average