Task: Program Execution
Input (English): 18, 19, ['r', '8611', 'b', 'R', 'p', 'W', '8021', 'x', '1153', '985', 'W', '7913', '8263', 'l', 'p', 'X', 'w', 'Z', '6635']
Output (English): 6635Z