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, 20, ['R', '3903', 'A', 'T', 'M', 'r', 'j', 'K', '7633', 'i', '487', '9923', 'I', 'j', '5757', '5581', '5005', 'J', '4339', 'R', 'H', 'h', 'o', '5607', 'x']

R4339J500555815757jI9923