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: 12, 18, ['O', 'l', '6187', '8145', 'B', '2127', '5985', 'l', '9543', 'U', 'J', '4521', 'X', '3665', '5769', '5723', '9047', 'i', 'j']

i9047572357693665X4521