Task: Program Execution
Input (English): 3, 20, ['x', 'S', 's', 'a', '5077', 'D', '3979', 'I', '3129', 'R', '8517', 'r', 'l', 'K', 'N', '9701', '227', 'n', '9385', 'U']
Output (English): U5839n7221079NKlr7158R9213I9793D7705as