Task: Program Execution
Input (English): 17, 18, ['8043', 'N', '3493', '8561', 'q', 'u', '6219', '159', '4569', 'R', '7169', '2857', 'C', '757', '4947', '9821', 'S', '2509', '511', 'p', '9421']
Output (English): 2509S