Task: Program Execution
Input (English): r, B, 2, B, 5, f
Output (English): [['r', 'B', '2', 'B', '5'], ['r', 'B', '2', 'B', 'f'], ['r', 'B', '2', '5', 'f'], ['r', 'B', 'B', '5', 'f'], ['r', '2', 'B', '5', 'f'], ['B', '2', 'B', '5', 'f']]