In this task, you are given inputs 'i', 'j', and A, where 'i' and 'j' are integers and A is a list. A list is shown by two brackets and comma-separated numbers and characters inside, like ['1', '12', 'l']. You need to concatenate all elements of A from the ith element to the jth element, and then reverse the resulting 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 reverse first and then concatenate.
12, 20, ['U', '7137', '6321', '3917', '3191', 'V', '9187', '4767', 'q', '6027', 'x', 'y', 't', 'J', 'X', '2755', '8833', '1377', 'D', 'P', 'G', '125', '5307']