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: 20, 21, ['D', 'B', 'j', '5971', '8339', '3269', '653', 'y', '8069', '6197', 'j', 's', '6143', 'G', 'i', '4857', 'O', '7781', 'Q', '3445', '5543', '1693', 'l', 'v', 'd', 'k']

55433445