For each test case, print a line containing the test case number (beginning with 1) followed by one integerM, indicating the number of operations needed. You must assure thatMis no larger than 5N. If you cannot find a solution, makeMequal to -1 and ignore the following output.
In the nextMlines, each contains two integersiandj(1 ≤i<j≤N), indicating an operation, separated by one space.
If there are multiple answers, you can print any of them.
Remember to print a blank line after each case. But extra spaces and blank lines are not allowed.
，我们大都接受的是正面的教育，
