Definition: In this task, you are given inputs i, j, and A, where i and j are integers and A is a list. You need to find all elements of A from the ith element to the jth element, reverse the order in which they occur, and then concatenate them to output the resultant string. i and j will be non-negative, and will always have a value less than the length of A. i will always be less than j. Perform the operations in order, i.e., do not concatenate the elements and then reverse the string.
Input: 15, 21, ['v', 't', '4437', '8433', 'e', '5355', 'R', 'm', 'g', 'z', 'g', '3967', 'I', '1939', '9819', 'O', '7669', 'Q', '2359', 'O', '8057', '777', '4517', 'F', 'v', '9421', 'e']

8057O2359Q7669O9819