Task: Program Execution
Input (English): 5, 6, ['C', '2155', '4217', 'L', 'S', '3981', '7395', 't', '8391', 'U', '6173', '4343', '523', 'f', 'I', '2943', 'o', '8487', 'K', '5155']
Output (English): S3981