Task: Program Execution
Input (English): 20, 21, ['375', 'Z', 'K', '5223', 'D', 'z', 'n', '6075', 'b', 'g', '2505', '329', '3221', 'P', '8117', '7847', '4287', 'a', '5117', 'c', 'z', 'v']
Output (English): zc