TASK DEFINITION: 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.
PROBLEM: 2, 2, ['6099', 'r']

SOLUTION: r

PROBLEM: 4, 16, ['M', '1253', 'L', '1997', 'E', 'u', '4953', '1627', '4497', '1839', 'M', 's', '9821', '9159', '845', '6189', 'F', 'G', 'E', '2303', '503']

SOLUTION: 981654895191289sM9381794472613594uE7991

PROBLEM: 5, 20, ['7269', '9781', '4273', '3427', '1357', 'W', 'u', '2959', '4137', 'V', 'T', '4221', 'X', 'L', '5765', 'B', 'c', '7231', '7957', '3421', 'l', 'E', '5199', '4597', 'U', 'O', '4387']

SOLUTION:
124375971327cB5675LX1224TV73149592uW7531