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: 3, 12, ['4187', '2027', '1157', 'x', 'M', 't', '7321', 's', 'c', '9831', '2137', 'H', '241', '7201', 'i', 't', 'x', 'k', 'r', '419']

H21379831cs7321tMx1157