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.
import java.io.*;
import java.util.*;
import java.math.*;
import java.lang.*;
 
import static java.lang.Math.*;
 
public class Cf182 implements Runnable 
{
	static class InputReader 
	{
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;
		private SpaceCharFilter filter;
		private BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		public InputReader(InputStream stream) 
		{
			this.stream = stream;
		}
		
		public int read()
		{
			if (numChars==-1) 
				throw new InputMismatchException();
            
			if (curChar >= numChars) 
			{
				curChar = 0;
				try
				{
					numChars = stream.read(buf);
				}
				catch (IOException e)
				{
					throw new InputMismatchException();
				}
                
				if(numChars <= 0)               
					return -1;
			}
			return buf[curChar++];
		}
     
		public String nextLine()
		{
			String str = "";
			try
			{
				str = br.readLine();
			}
			catch (IOException e)
			{
				e.printStackTrace();
			}	
			return str;
		}
		public int nextInt() 
		{
			int c = read();
            
			while(isSpaceChar(c)) 
				c = read();
		
			int sgn = 1;
        
			if (c == '-') 
			{
				sgn = -1;
				c = read();
			}
            
			int res = 0;
			do
			{
				if(c<'0'||c>'9') 
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			}
			while (!isSpaceChar(c)); 
        
			return res * sgn;
		}
        
		public long nextLong() 
		{
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-')
			{
				sgn = -1;
				c = read();
			}
			long res = 0;
			
			do 
			{
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			}	
			while (!isSpaceChar(c));
				return res * sgn;
		}
		
		public double nextDouble() 
		{
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-')
			{
				sgn = -1;
				c = read();
			}
			double res = 0;
			while (!isSpaceChar(c) && c != '.') 
			{
				if (c == 'e' || c == 'E')
					return res * Math.pow(10, nextInt());
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			}
			if (c == '.') 
			{
				c = read();
				double m = 1;
				while (!isSpaceChar(c))
				{
					if (c == 'e' || c == 'E')
						return res * Math.pow(10, nextInt());
					if (c < '0' || c > '9')
						throw new InputMismatchException();
					m /= 10;
					res += (c - '0') * m;
					c = read();
				}
			}
			return res * sgn;
		}
    
		public String readString() 
		{
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do 
			{
				res.appendCodePoint(c);
				c = read();
			} 
			while (!isSpaceChar(c));
            
			return res.toString();
		}
     
		public boolean isSpaceChar(int c) 
		{
			if (filter != null)
				return filter.isSpaceChar(c);
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
     
		public String next()
		{
			return readString();
		}
        
		public interface SpaceCharFilter
		{
			public boolean isSpaceChar(int ch);
		}
	}
	public static void main(String args[]) throws Exception 
	{
		new Thread(null, new Cf182(),"Main",1<<27).start();
	}	
	
	public static long gcd(long a, long b) 
	{ 
		if (a == 0) 
			return b; 
		return gcd(b % a, a); 
	} 
	//  array sorting by colm
public static void sortbyColumn(int arr[][], int col) 
    { 
        
        Arrays.sort(arr, new Comparator<int[]>() { 
            
          @Override
          public int compare(final int[] entry1,  
                             final int[] entry2) { 
  
           
            if (entry1[col] > entry2[col]) 
                return 1; 
            else
                return -1; 
          } 
        });  
    } 
	
	// gcd
  
	public static long findGCD(long arr[], int n) 
	{ 
		long result = arr[0]; 
		for (int i = 1; i < n; i++) 
			result = gcd(arr[i], result); 
		return result; 
	}
	// fibonaci
	static int fib(int n) 
    { 
        int a = 0, b = 1, c; 
        if (n == 0) 
            return a; 
        for (int i = 2; i <= n; i++) 
        { 
            c = a + b; 
            a = b; 
            b = c; 
        } 
        return b; 
    } 
    
// sort a string
    public static String sortString(String inputString) 
    { 
        
        char tempArray[] = inputString.toCharArray(); 
          
         
        Arrays.sort(tempArray); 
          
         
        return new String(tempArray); 
    } 
    // pair function
    
    // list.add(new Pair<>(sc.nextInt(), i + 1));
    //     Collections.sort(list, (a, b) -> Integer.compare(b.first, a.first));
    private static class Pair<F, S> {
 
        private F first;
 
        private S second;
 
        public Pair() {}
 
        public Pair(F first, S second) {
            this.first = first;
            this.second = second;
        }
    }
    
	// SortedArrayList<Integer> test = new SortedArrayList<Integer>();
    // test.insert(5); 
            public static class SortedArrayList<T> extends ArrayList<T> {
        
            @SuppressWarnings("unchecked")
            public void insert(T value) {
                add(value);
                Comparable<T> cmp = (Comparable<T>) value;
                for (int i = size()-1; i > 0 && cmp.compareTo(get(i-1)) < 0; i--)
                    Collections.swap(this, i, i-1);
            }
        }
    
	
	public void run()
	{
		InputReader sc = new InputReader(System.in);
		PrintWriter w = new PrintWriter(System.out);
	    int t = sc.nextInt();
	    while(t--!=0)
	    {
	        int n = sc.nextInt();
	        char a[] = sc.next().toCharArray();
	        char b[] = sc.next().toCharArray();
	        ArrayList<Integer> ans = new ArrayList<>();
	        for(int i=n-1;i>=0;i--)
	        {
	            
	            if(i==0)
	            {
	                if(a[0]!=b[0])
	                {
	                    ans.add(1);
	                    break;
	                }
	            }
	            if(a[i]!=b[i])
	            {
	                if(a[0]!=b[i])
	                    ans.add(i+1);
	                else
	                {
	                    ans.add(1);
	                    ans.add(i+1);
	                    if(b[i]=='0')
	                        a[0] = '1';
	                    else
	                        a[0] = '0';
	                }
	                
	                for(int j=0;j<=i/2;j++)
	                {
	                    if(j==i/2 && i%2==0)
	                    {
	                        if(a[j]=='0')
	                            a[j] = '1';
	                        else
	                            a[j] = '0';
	                        break;
	                    }
	                    char temp = a[j];
	                    a[j] = a[i - j];
	                    a[i - j] = temp;
	                    if(a[j]=='0')
	                        a[j] = '1';
	                    else
	                        a[j] = '0';
	                   if(a[i - j]=='0')
	                        a[i - j] = '1';
	                    else
	                        a[i - j] = '0';
	                }
	            }
	        }
	        w.print(ans.size()+" ");
	        for(int i:ans)
	            w.print(i+" ");
	        w.println();
	    }
        w.flush();
	    w.close();
	}
}
