Task: Program Execution
Input (English): 15, 16, ['4339', '5397', '4993', '4555', '9951', '6877', 'E', 'G', 'O', '3587', 'n', '9553', '7773', 'e', 'F', 'U', '5463', 'b', '7759', 'M', 'I', 'X', 'G', 'B']
Output (English): UF