A. Make It Zerotime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputDuring Zhongkao examination, Reycloer met an interesting problem, but he cannot come up with a solution immediately. Time is running out! Please help him.Initially, you are given an array a consisting of n \ge 2 integers, and you want to change all elements in it to 0.In one operation, you select two indices l and r (1\le l\le r\le n) and do the following:  Let s=a_l\oplus a_{l+1}\oplus \ldots \oplus a_r, where \oplus denotes the bitwise XOR operation;  Then, for all l\le i\le r, replace a_i with s. You can use the operation above in any order at most 8 times in total.Find a sequence of operations, such that after performing the operations in order, all elements in a are equal to 0. It can be proven that the solution always exists.InputThe first line of input contains a single integer t (1\le t\le 500) — the number of test cases. The description of test cases follows.The first line of each test case contains a single integer n (2\le n\le 100) — the length of the array a.The second line of each test case contains n integers a_1,a_2,\ldots,a_n (0\le a_i\le 100) — the elements of the array a.OutputFor each test case, in the first line output a single integer k (0\le k\le 8) — the number of operations you use.Then print k lines, in the i-th line output two integers l_i and r_i (1\le l_i\le r_i\le n) representing that you select l_i and r_i in the i-th operation. Note that you do not have to minimize k. If there are multiple solutions, you may output any of them.ExampleInput
641 2 3 083 1 4 1 5 9 2 661 5 4 1 4 750 0 0 0 071 1 9 9 0 1 83100 100 0Output
1
1 4
2
4 7
1 8
6
1 2
3 4
5 6
1 3
4 6
1 6
0
4
1 2
6 7
3 4
6 7
1
1 2
NoteIn the first test case, since 1\oplus2\oplus3\oplus0=0, after performing the operation on segment [1,4], all the elements in the array are equal to 0.In the second test case, after the first operation, the array becomes equal to [3,1,4,15,15,15,15,6], after the second operation, the array becomes equal to [0,0,0,0,0,0,0,0].In the third test case: Operationa beforea after1[\underline{1,5},4,1,4,7]\rightarrow[4,4,4,1,4,7]2[4,4,\underline{4,1},4,7]\rightarrow[4,4,5,5,4,7]3[4,4,5,5,\underline{4,7}]\rightarrow[4,4,5,5,3,3]4[\underline{4,4,5},5,3,3]\rightarrow[5,5,5,5,3,3]5[5,5,5,\underline{5,3,3}]\rightarrow[5,5,5,5,5,5]6[\underline{5,5,5,5,5,5}]\rightarrow[0,0,0,0,0,0] In the fourth test case, the initial array contains only 0, so we do not need to perform any operations with it.
641 2 3 083 1 4 1 5 9 2 661 5 4 1 4 750 0 0 0 071 1 9 9 0 1 83100 100 0
1 1 4 2 4 7 1 8 6 1 2 3 4 5 6 1 3 4 6 1 6 0 4 1 2 6 7 3 4 6 7 1 1 2 
['constructive algorithms', '*900']