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.*;

public class Cf131 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 Cf131(),"Main",1<<27).start();
    }
    
    static class Pair{
        int nod;
        int ucn;
        
        
        Pair(int nod,int ucn){
            this.nod=nod;
            this.ucn=ucn;
            
        }
        
        public static Comparator<Pair> wc = new Comparator<Pair>(){
            public int compare(Pair e1,Pair e2){
                
                //reverse order
                if(e1.ucn < e2.ucn) 
                    return 1;  // 1 for swaping.
                else if (e1.ucn > e2.ucn) 
                    return -1; 
                else{
                    // if(e1.siz>e2.siz)
                    //     return 1;
                    // else
                    //     return -1;
                    return 0;
                } 
            }
        };	
    }

    public static long gcd(long a,long b){
        if(b==0)return a;
        else return gcd(b,a%b);
    }


    ////recursive BFS
    public static int bfsr(int s,ArrayList<Integer>[] a,int[] dist,boolean[] b,int[] pre){
        b[s]=true;
        int p = 0;
        int t = a[s].size();
        for(int i=0;i<t;i++){
            int x = a[s].get(i);
            if(!b[x]){
                dist[x] = dist[s] + 1;
                p+= (bfsr(x,a,dist,b,pre)+1);
            }
        }
        pre[s] = p;
        return p;
    }

//// iterative BFS
    public static int bfs(int s,ArrayList<Integer>[] a,int[] dist,boolean[] b,PrintWriter w){
        b[s]=true;
        int siz = 0;
        
        Queue<Integer> q = new LinkedList<>();
        q.add(s);
        while(q.size()!=0){
            int i=q.poll();
            Iterator<Integer> it = a[i].listIterator();
            int z=0;
            while(it.hasNext()){
                z=it.next();
                if(!b[z]){
                    b[z]=true;
                    dist[z] = dist[i] + 1;
                    siz++;
                    q.add(z);
                }
            }   
        
        }
        return siz;
    }

    public static void alter(char[] a, int k){
        int l = 0;
        int r = k-1;
        while(r>l){
            char temp = a[r];
            if(a[l]=='0')a[r]='1';
            else a[r] = '0';

            if(temp=='0')a[l]='1';
            else a[l] = '0';  
            
            l++;
            r--;
        }
        if(l==r){
           if(a[l]=='0')a[r]='1';
            else a[r] = '0';
        }
    }




//////////////////////////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////////////////////////


    public void run()
    {
        InputReader sc = new InputReader(System.in);
        PrintWriter w = new PrintWriter(System.out);
        int defaultValue=0;
        
        int t = sc.nextInt();

        while(t-->0){
            int n = sc.nextInt();
            
            String aa = sc.next();
            char[] a = aa.toCharArray();
            String bb = sc.next();
            char[] b = bb.toCharArray();
            ArrayList<Integer> ans = new ArrayList<Integer>();
            if(!aa.equals(bb)){
                for(int i=0;i<n-1;i++){
                    if(a[0]!=b[i]){
                        ans.add(1);
                        a[0] = b[i];
                    }
                    
                    alter(a,n-i);
                    ans.add(n-i);
                    
                }
                if(a[0]==b[n-1]){
                    ans.add(1);
                     alter(a,1);
                    //a[0] = b[n-1];
                }
                ans.add(n);
                alter(a,n);
                int z = ans.size();
                w.print(z+" ");
                for(int i=0;i<z;i++){
                    w.print(ans.get(i)+" ");
                }
                w.println("");
            }
            else{
                w.println("0");
            }
            
            // for(int i=0;i<n;i++){
            //     w.print(b[i]);
            // }
            // w.println("");
            // for(int i=0;i<n;i++){
            //     w.print(a[i]);
            // }
            // w.println("");



        }
        w.flush();
        w.close();
    }

}