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.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.StringTokenizer;



public class Main {

  public static PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));

  static class Pair {

    final String first, second;

    Pair(String first, String second) {
      this.first = first;
      this.second = second;
    }
  }


  static class FastReader {

    BufferedReader br;
    StringTokenizer st;

    public FastReader() {
      br = new BufferedReader(new
          InputStreamReader(System.in));
    }

    String next() {
      while (st == null || !st.hasMoreElements()) {
        try {
          st = new StringTokenizer(br.readLine());
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      return st.nextToken();
    }

    int nextInt() {
      return Integer.parseInt(next());
    }

    long nextLong() {
      return Long.parseLong(next());
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    String[] nextSArray() {
      String sr[] = null;
      try {
        sr = br.readLine().trim().split(" ");
      } catch (IOException e) {
        e.printStackTrace();
      }
      return sr;
    }

    String nextLine() {
      String str = "";
      try {
        str = br.readLine();
      } catch (IOException e) {
        e.printStackTrace();
      }

      return str;
    }
  }


  public static void main(String[] args) throws Exception {
    FastReader sc = new FastReader();



    int t1 = sc.nextInt();
    for (int t = 0; t < t1; ++t) {
      int n=sc.nextInt();
      String a=sc.nextLine();
      String b=sc.nextLine();
      int []arr=new int[n];
      int []brr=new int[n];
      for(int i=0;i<n;++i)
      {
        arr[i]=a.charAt(i)-48;
        brr[i]=b.charAt(i)-48;
        //System.out.println(arr[i]+" "+brr[i]);
      }
      ArrayList<Integer>ans=new ArrayList<>();
      for(int i=n-1;i>=0;--i)
      {
//        for (int k = 0; k < n; ++k) {
//          System.out.print(arr[k]);
//        }
//        System.out.println();
//        System.out.println(i);
//        System.out.println();
        if(arr[i]==brr[i])
          continue;
        else
        {
          int c=arr[0];
          c=(c+1)%2;
          if(c==brr[i])
          {
            ans.add(i+1);
            for(int j=0;j<Math.ceil((i+1)/2.0);++j)
            {
              int temp=arr[j];
              arr[j]=(arr[i-j]+1)%2;
              arr[i-j]=(temp+1)%2;
            }
          }
          else
          {
            ans.add(1);
          ans.add(i+1);
            arr[0]=(arr[0]+1)%2;
            for(int j=0;j<Math.ceil((i+1)/2.0);++j)
            {
              int temp=arr[j];
              arr[j]=(arr[i-j]+1)%2;
              arr[i-j]=(temp+1)%2;
            }
          }

        }
      }
      out.println(ans.size()+" "+ans.toString().replaceAll("[\\[|\\]|,]",""));
    }

    out.close();
  }
}
// out.println(al.toString().replaceAll("[\\[|\\]|,]",""));