There are persons in Bytetown, with the -th person having an item of type . These persons want to exchange items with each other through the following operation:

• Choose two persons , exchange the item owned by the -th person and the -th person.
  

They want to perform this operation exactly once between each pair of persons with . At the end of this sequence of operations, the -th person wants to own an item of type . They want to know if there exists a sequence of operation achieving this requirement. Can you help them?

输入描述:

The first line contains an integer  (), denoting the number of test cases.

For each test case, the first line contains an integer , denoting the number of persons in Bytetown.

The second line contains  integers , where  denotes the item initially owned by the -th person.

The third line contains  integers , where  denotes the item desired by the -th person.

It is guaranteed that the sum of  does not exceed .

输出描述:

For each test case, if there doesn't exist a sequence of operation achieving this requirement, output "NO"(without quotes) in a line. Otherwise, output "YES"(without quotes) in a line, then output a sequence of operation achieving the requirement in  lines, where the th line contains two integers , denoting the -th operation in the sequence.

2
2
1 2
1 2
2
2 1
1 2

NO
YES
1 2