Task: Program Execution
Input (English): 19, 21, ['2245', '7355', 'k', '3959', '5641', 't', '9095', '7763', '8571', 'W', 'm', 'z', 'G', '7599', '1433', 'F', 'w', '1083', 'B', '5627', 'U', 'b']
Output (English): U5627B