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.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.*;

import java.io.*;
	

	
public class cf {
	static InputReader obj = new InputReader(System.in);
	static long mod = (long)1e9+7;
	public static void main(String args[]) {
		main();
	}
	
	static void main() {
		int t=obj.nextInt();
		
		while(t-->0) {
			int n=obj.nextInt();
			String a1 = obj.next();
			String b1 = obj.next();
			char a[] = a1.toCharArray();
			char b[] = b1.toCharArray();
			int i=0;
			int j=n-1;
			ArrayList<Integer> ans = new ArrayList<Integer>();
			while(j>=0) {
				i=0;
				int k=j;
				if(a[i]==b[j]) {
					ans.add(1);
					a[i] = (char)('1'+'0'-a[i]);
				}
				while(j>=0 && a[i]!=b[j]) {
					i++;
					j--;
				}
				rev(a, k);
				ans.add(k+1);
			}
			int e=ans.size();
			System.out.print(e+" ");
			for(int x: ans) {
				System.out.print(x+" ");
			}
			System.out.println();
		}
		
	}
	
	public static void rev(char a[], int k) {
		int n=a.length;
		for(int i=0;i<=k/2;i++) {
			char temp=a[i];
			a[i] = (char)('1'+'0'-a[k-i]);
			a[k-i] = (char)('1'+'0'-temp);
		}
	}
	
	
	public static void input(int arr[], int n) {
		for(int i=0;i<n;i++) {
	    	arr[i] = obj.nextInt();
	    }
	}
	
	public static class InputReader {
	    public BufferedReader reader;
	    public StringTokenizer tokenizer;
	    public InputReader(InputStream stream) {
	        reader = new BufferedReader(new InputStreamReader(stream), 32768);
	        tokenizer = null;
	    }
 
	    public String next() {
	        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
	            try {
	                tokenizer = new StringTokenizer(reader.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }
	        return tokenizer.nextToken();
	    }
 
	    public int nextInt() {
	        return Integer.parseInt(next());
	    }
 
	    public long nextLong() {
	        return Long.parseLong(next());
	    }
	}

}