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]: 2, 2, ['6099', 'r']
[EX A]: r

[EX Q]: 18, 20, ['5263', '7963', '8931', 'I', 'n', '8167', 'A', '5429', 'O', '6539', '7303', 'V', 'l', 'd', 's', '8377', 'Z', '7345', 'X', 'D', '6125', 'c', 'o', 'x', 'I', '2807', '3995', '3297', 'O']
[EX A]: DX5437

[EX Q]: 1, 1, ['G', 'd', '2919', '1395']
[EX A]:
G