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.
6, 21, ['X', 'X', 'p', '4701', '655', 'o', '4457', 'd', '6861', '9839', '4973', 'M', '9239', '5911', 'W', '2197', 'z', '8635', 'C', '4969', 'J', 'B', '4487', '3021', 'v', 'P']