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 A {
    static Scanner sc = new Scanner(System.in);
    static PrintWriter pw = new PrintWriter(System.out);


    static void solve() {
        int n = sc.nextInt();
        String a = sc.next();
        String b = sc.next();
        int sum = 0;
        ArrayList<Integer> indexes = new ArrayList<>();
        ArrayList<Integer> reverse = new ArrayList<>();
        for (int i = 0; i < n - 1; i ++){
            if (a.charAt(i) != a.charAt(i + 1)){
                sum += 1;
                indexes.add(i);
            }
            if (b.charAt(i) != b.charAt(i + 1)){
                sum += 1;
                reverse.add(0, i);
            }
        }
        if (a.charAt(n - 1) == '1'){
            indexes.add(n - 1);
            sum += 1;
        }
        if (b.charAt(n - 1) == '1'){
            reverse.add(0, n - 1);
            sum += 1;
        }
        pw.print(sum + " ");
        for (int i: indexes) {
            pw.print(String.valueOf(i + 1) + " ");
        }
        for (int i: reverse){
            pw.print(String.valueOf(i + 1) + " ");
        }
        pw.println();
    }

    public static void main(String[] args){
        int t = sc.nextInt();
        for (int i = 0; i < t; i ++){
            solve();
        }
        pw.close();
    }

}