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.*;

public class twoteams{
    public static void main(String args[]){
        Scanner input = new Scanner(System.in);
        int length = Integer.parseInt(input.next());
        int [] a = new int [1000];
        int [] b = new int [1000];
        int [] sol = new int [3000];
        int count;
        int chunk;
        String temp;
        for(int i = 0; i < length; i++){
            count = 0;
            chunk = Integer.parseInt(input.next());
            temp = input.next();
            for(int j = 0; j < chunk; j++){
                a[j] = Integer.parseInt(String.valueOf(temp.charAt(j)));
            }
            temp = input.next();
            for(int j = 0; j < chunk; j++){
                b[j] = Integer.parseInt(String.valueOf(temp.charAt(j)));
            }
            for(int j = 0; j < chunk; j++){
                if(a[j] != b[j]){
                    sol[count] = j+1;
                    count++;
                    sol[count] = 1;
                    count++;
                    sol[count] = j+1;
                    count++;
                }
            }
            System.out.print(count + " ");
            for(int j = 0; j < count; j++){
                System.out.print(sol[j]+" ");
            }
            System.out.print("\n");
        }
        input.close();
    }
}