Task: Program Execution
Input (English): 1, 5, ['8419', '9975', 't', 'x', '7869', 'd', '6515', '4873', '4519', '899', 'Z', 'X', 'l', 'r', '743', 'N', 'a', '4231', 'W', 'm', '3517', '7539']
Output (English): 7869xt99758419