Description:
During 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.
Input Format:
The 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 $$$a$$$.
Output Format:
For 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.
Note:
In 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:
Operation$$$a$$$ before$$$a$$$ after$$$1$$$$$$[\underline{1,5},4,1,4,7]$$$$$$\rightarrow$$$$$$[4,4,4,1,4,7]$$$$$$2$$$$$$[4,4,\underline{4,1},4,7]$$$$$$\rightarrow$$$$$$[4,4,5,5,4,7]$$$$$$3$$$$$$[4,4,5,5,\underline{4,7}]$$$$$$\rightarrow$$$$$$[4,4,5,5,3,3]$$$$$$4$$$$$$[\underline{4,4,5},5,3,3]$$$$$$\rightarrow$$$$$$[5,5,5,5,3,3]$$$$$$5$$$$$$[5,5,5,\underline{5,3,3}]$$$$$$\rightarrow$$$$$$[5,5,5,5,5,5]$$$$$$6$$$$$$[\underline{5,5,5,5,5,5}]$$$$$$\rightarrow$$$$$$[0,0,0,0,0,0]$$$
In the fourth test case, the initial array contains only $$$0$$$, so we do not need to perform any operations with it.