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: 8, 21, ['7449', 'R', '469', 'm', 'A', '817', '9583', '239', 'n', '3597', 'C', '6853', '2745', '3827', '5775', 'x', '3875', '7503', '8903', '9679', '819']

8199679890375033875x5775382727456853C3597n239