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.
18, 20, ['6907', 'q', 'Y', '6647', 'o', 'J', '6479', '3585', '2265', '3515', '9353', 'Z', '5359', '5717', '4389', '5753', '9', 'G', 'l', '7003', 'p']