Task: Program Execution
Input (English): U, k, 1, f, q, 4
Output (English): [['U', 'k', '1', 'f', 'q'], ['U', 'k', '1', 'f', '4'], ['U', 'k', '1', 'q', '4'], ['U', 'k', 'f', 'q', '4'], ['U', '1', 'f', 'q', '4'], ['k', '1', 'f', 'q', '4']]