Problem: This is the easy version of the problem. The difference between the versions is the constraint on n and the required number of operations. You can make hacks only if all versions of the problem are solved.

There are two binary strings a and b of length n (a binary string is a string consisting of symbols 0 and 1). In an operation, you select a prefix of a, and simultaneously invert the bits in the prefix (0 changes to 1 and 1 changes to 0) and reverse the order of the bits in the prefix.

For example, if a=001011 and you select the prefix of length 3, it becomes 011011. Then if you select the entire string, it becomes 001001.

Your task is to transform the string a into b in at most 3n operations. It can be proved that it is always possible.

Input

The first line contains a single integer t (1≤ t≤ 1000) — the number of test cases. Next 3t lines contain descriptions of test cases.

The first line of each test case contains a single integer n (1≤ n≤ 1000) — the length of the binary strings.

The next two lines contain two binary strings a and b of length n.

It is guaranteed that the sum of n across all test cases does not exceed 1000.

Output

For each test case, output an integer k (0≤ k≤ 3n), followed by k integers p_1,…,p_k (1≤ p_i≤ n). Here k is the number of operations you use and p_i is the length of the prefix you flip in the i-th operation.

Example

Input


5
2
01
10
5
01011
11100
2
01
01
10
0110011011
1000110100
1
0
1


Output


3 1 2 1
6 5 2 5 3 1 2
0
9 4 1 2 10 4 1 2 1 5
1 1

Note

In the first test case, we have 01→ 11→ 00→ 10.

In the second test case, we have 01011→ 00101→ 11101→ 01000→ 10100→ 00100→ 11100.

In the third test case, the strings are already the same. Another solution is to flip the prefix of length 2, which will leave a unchanged.

Solution (in JAVA):

Solution:
import java.util.*;
import java.io.*;

public class Solution{

     public static void main(String []args){
        Scanner sc = new Scanner(System.in);
        
        int t = sc.nextInt();
        
        while(t > 0){
            
            int n = sc.nextInt();
            String s1 = sc.next();
            String s2 = sc.next();
            //System.out.println(s1 + " " + s2);
            List<Integer> res= new ArrayList<>();
            
            int ptr = 0;
            
            for(int i = 0 ; i < n ; i++) {
                
                char c1 = s1.charAt(i);
                char c2 = s2.charAt(i);
                
                
                if(c1 == c2){
                    continue;
                }
                
                else{
                    res.add(i+1);
                    res.add(1);
                    res.add(i+1);
                    
                }
                
            }
            
            System.out.print(res.size() + " ");
            
            for(int i : res){
                System.out.print(i +" ");
            }
            System.out.println();
            t -= 1;
        }
        
        
        
        
          
      }
      
     
}