Task: Program Execution
Input (English): 20, 21, ['u', 'd', 'Q', '9049', '3975', 'f', 'N', 'j', '7723', '865', '5459', 'X', 'n', '2037', 'Y', '2611', 'u', 'Z', '5045', '6635', 'E']
Output (English): 6635E