Task: Program Execution
Input (English): 6, 13, ['P', 't', '9221', 'L', '4037', '8527', '4783', '9029', '6053', '3023', 'B', 'U', 'u', 'E']
Output (English): u, U, B, 3023, 6053, 9029, 4783, 8527