B'An array b of m positive integers is good if for all pairs i and j ( 1 <= q i,j <= q m ), max(b_i,b_j) is divisible by min(b_i,b_j) . You are given an array a of n positive integers. You can perform the following operation: You have to construct a sequence of at most n operations that will make a good. It can be proven that under the constraints of the problem, such a sequence of operations always exists. Each test contains multiple test cases. The first line contains a single integer t ( 1 <= q t <= q 10^4 ) -- the number of test cases. The description of the test cases follows. The first line of each test case contains a single integer n ( 1 <= q n <= q 10^5 ) -- the length of the array a . The second line of each test case contains n space-separated integers a_1,a_2, ldots,a_n ( 1 <= q a_i <= q 10^9 ) -- representing the array a . It is guaranteed that the sum of n over all test cases does not exceed 10^5 . For each test, output a single integer p ( 0 <= q p <= q n ) -- denoting the number of operations in your solution. In each of the following p lines, output two space-separated integers -- i and x . You do not need to minimize the number of operations. It can be proven that a solution always exists. In the first test case, array a becomes [5,5,5,5] after the operations. It is easy to see that [5,5,5,5] is good. In the second test case, array a is already good. In the third test case, after performing the operations, array a becomes [10,5,350,5,10] , which is good. In the fourth test case, after performing the operations, array a becomes [60,10,20] , which is good. '...