Task: Program Execution
Input (English): S, r, Z, 1, 5, 2, U
Output (English): [['S', 'r', 'Z', '1', '5', '2'], ['S', 'r', 'Z', '1', '5', 'U'], ['S', 'r', 'Z', '1', '2', 'U'], ['S', 'r', 'Z', '5', '2', 'U'], ['S', 'r', '1', '5', '2', 'U'], ['S', 'Z', '1', '5', '2', 'U'], ['r', 'Z', '1', '5', '2', 'U']]