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.

[EX Q]: 7, 18, ['4879', '857', 'X', '8629', 'K', 'l', 'U', '5611', '5989', '4439', '4897', 'D', 'p', '8109', 'F', 'a', '4665', 'Q']
[EX A]: Q5664aF9018pD7984934498951165U

[EX Q]: 3, 3, ['5819', '3317', '451', '5811']
[EX A]: 154

[EX Q]: 4, 4, ['n', '7785', 'd', '7249', '4047', 't', 'G', '3071', '7475', '249']
[EX A]:
9427