B"Numbers 1, 2, 3, ... n (each integer from 1 to n once) are written on a board. In one operation you can erase any two numbers a and b from the board and write one integer frac{a + b}{2} rounded up instead. You should perform the given operation n - 1 times and make the resulting number that will be left on the board as small as possible. For example, if n = 4 , the following course of action is optimal: It's easy to see that after n - 1 operations, there will be left only one number. Your goal is to minimize it. The first line contains one integer t ( 1 <= t <= 1000 ) -- the number of test cases. The only line of each test case contains one integer n ( 2 <= n <= 2 cdot 10^5 ) -- the number of integers written on the board initially. It's guaranteed that the total sum of n over test cases doesn't exceed 2 cdot 10^5 . For each test case, in the first line, print the minimum possible number left on the board after n - 1 operations. Each of the next n - 1 lines should contain two integers -- numbers a and b chosen and erased in each operation. "...