Task: Program Execution
Input (English): 2, X, 4, U, f, F, 6
Output (English): [['2', 'X', '4', 'U', 'f', 'F'], ['2', 'X', '4', 'U', 'f', '6'], ['2', 'X', '4', 'U', 'F', '6'], ['2', 'X', '4', 'f', 'F', '6'], ['2', 'X', 'U', 'f', 'F', '6'], ['2', '4', 'U', 'f', 'F', '6'], ['X', '4', 'U', 'f', 'F', '6']]