Definition: In this task, you are given inputs i, j, and A, where i and j are integers and A is a list. You need to find all elements of A from the ith element to the jth element, reverse the order in which they occur, and then concatenate them to output the resultant 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 concatenate the elements and then reverse the string.
Input: 12, 20, ['1569', 'z', 'X', 'u', 'j', '3509', '8555', '9473', 'R', '1447', '7237', 'E', '2391', '5415', 'Q', '6967', 'C', '5305', '1775', '6669', '5079']

666917755305C6967Q54152391E