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.awt.Desktop;

import java.io.BufferedReader;


import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import java.net.URISyntaxException;
import java.sql.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Scanner;
import java.util.Set;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeSet;
import java.util.Vector;



public  class codechef3 {
static class comp implements Comparator<Integer>
{

	@Override
	public int compare(Integer o1, Integer o2) {
		if(Math.abs(o1)>Math.abs(o2))
			return -1;
		else return 1;
	
	}

	
	}
	   

		 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 nextLine() 
		        { 
		            String str = ""; 
		            try
		            { 
		                str = br.readLine(); 
		            } 
		            catch (IOException e) 
		            { 
		                e.printStackTrace(); 
		            } 
		            return str; 
		        } 
		    } 
		 public static boolean check(long n,int d)
		 {
			 while(n>0)
			 {
				long r=n%10;
				 if(r==d)
					 return true;
				 n=n/10;
			 }
			 return false;
		 }
		 public static int gcd(int a, int b)
		    {
		      if (b == 0)
		        return a;
		      return gcd(b, a % b); 
		    }
		    
		    public static void main(String[] args) 
		    {
		    	FastReader s=new FastReader();
	
		    	int t=s.nextInt();
		    	while(t-->0)
		    	{int n=s.nextInt();
		    	String a=s.next();
		    	String b=s.next();
		    	
		        
		    	ArrayList<Integer> l=new ArrayList<>();
		     
		        for(int i=0;i<n;i++)
		        {
		        	if(a.charAt(i)!=b.charAt(i))
		        	{
		        		if(i>0)
		        			l.add((i+1));
		        		l.add(1);
		        		if(i>0)
		        			l.add((i+1));
		        	}
		        	
		        	
		        	
		        }
		        System.out.print(l.size()+" ");
		        for(int i=0;i<l.size();i++)
		        {
		        	
		        	System.out.print(l.get(i)+" ");
		        }
		        System.out.println();
		      
		    	
		    	
		    	
		    	
		    	
		    		
		    	}
		    



}}