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.io.*;
import java.util.Arrays;
import java.util.*;

public class Main{
    
    public static void main(String[] args)throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int t = Integer.parseInt(br.readLine());
        while(t-->0){
            int n = Integer.parseInt(br.readLine());
            String a = br.readLine();
            String b = br.readLine();
            int count = 0;
            int[] solve = new int[3*n];
            char[] arr = a.toCharArray();
            char[] brr = b.toCharArray();
            for(int i=0; i<n; i++){
                int last = n-1-i;
                char need = brr[last];
                char we = arr[0];
                if(we==need){
                    arr[0] = (arr[0]=='0')?'1':'0';
                    we = arr[0];
                    solve[count++] = 1;
                }
                char[] temp = new char[n-i];
                int k =0;
                
                for(int j=n-i-1; j>=0; j--){
                    arr[j] = (arr[j]=='0')?'1':'0';
                    temp[k++] = arr[j];
                }
                for(int j=0; j<=last; j++){
                    arr[j] = temp[j];
                }
                solve[count++] = last+1;
            }
            System.out.print(count+" ");
            for(int i=0; i<count; i++){
                System.out.print(solve[i]+" ");
            }
            System.out.println();
            
        }
    }
}