instruction:
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.
question:
13, 15, ['L', 'A', '2959', 'g', '7157', '9131', 'o', 'D', 'q', 'd', 'A', '4249', 'K', 'U', '4805', 'h', '7981']
answer:
5084UK


question:
4, 20, ['H', '7451', 'X', 'i', '951', '1913', '9949', 'W', '4759', '1309', '1981', 'C', 'J', 'F', '4125', 'l', 'i', 'z', 'S', 'R', '5025', '5959', '1323', 'K', 'O', 'x', '5121', 'c', 'C']
answer:
RSzil5214FJC189190319574W94993191159i


question:
2, 2, ['e', '4007', '8645', 'A', '3981', 'a', '1219', 'C', 'D', 'X', '6715', 'e', 'M', 'g', 'J', 'y', 'Z', '4515', '8827', '1107']
answer:

7004