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.*;
import java.lang.*;
import java.io.*;

public class Codeforces {
    static FastReader sc=new FastReader();
	static PrintWriter out=new PrintWriter(System.out);
	static long mod=1000000007;
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		int t=I();
		while(t-->0)
		{
			StringBuffer sb=new StringBuffer();
			int n=I();
			long ans=0;
			String s1=S();
			String s2=S();
			for(int i=n-1;i>=0;i--){
				if(s1.charAt(i)==s2.charAt(i))continue;
				else{
					if(s1.charAt(0)==s2.charAt(i)){
						ans=ans+2;
						sb.append("1 ");
						s1=changeString(s1,1);
						sb.append((i+1)+" ");
						s1=changeString(s1,i+1);
					}else{
						ans=ans+1;
						sb.append((i+1)+" ");
						s1=changeString(s1,i+1);
					}
				}
			}
			if(ans==0){out.println("0");}
			else{
				out.print(ans+" ");
				out.println(sb.toString());
			}
		}
		// out.print(sb.toString());
		out.close();
	}
	public static String changeString(String s,int p)
	{
		char c[]=s.toCharArray();
		for(int i=0;i<p;i++){
			c[i]=c[i]=='1'?'0':'1';
		}
		for(int i=0;i<p/2;i++){
			char temp=c[i];
			c[i]=c[p-i-1];
			c[p-i-1]=temp;
		}
		StringBuffer sb=new StringBuffer();
		for(int i=0;i<c.length;i++){
			sb.append(c[i]);
		}
		return sb.toString();
	}
	public static void printArray(long a[])
	{
		for(int i=0;i<a.length;i++){
			out.print(a[i]+" ");
		}
		out.println();
	}
	public static void printArray(ArrayList<Integer> arr)
	{
		for(int i=0;i<arr.size();i++){
			out.print(arr.get(i)+" ");
		}
		out.println();
	}
	public static void DFS(ArrayList<Integer> arr[],int s,boolean visited[])
	{
		visited[s]=true;
		for(int i:arr[s]){
			if(!visited[i]){
				DFS(arr,i,visited);
			}
		}
	}
	public static int BS(long a[],long x,int ii,int jj)
	{
		// int n=a.length;
		int mid=0;
		int i=ii,j=jj;
		while(i<=j)
		{
			mid=(i+j)/2;
			if(a[mid]>x)
			j=mid-1;
			else if(a[mid]<=x)
			i=mid+1;
		}
		if(a[mid]>x && mid>ii)
		return mid-1;
		else
		return mid;
	}
	public static ArrayList<Integer> prime(int n)
	{
	    ArrayList<Integer> arr=new ArrayList<>();
	    boolean prime[] = new boolean[n + 1];
        for (int i = 0; i <= n; i++)
        prime[i] = true;
        for (int p = 2; p * p <= n; p++)
        {
            if (prime[p] == true)
            {
                for (int i = p * p; i <= n; i += p)
                prime[i] = false;
            }
        }
        for (int i = 2; i <= n; i++)
        {
            if (prime[i] == true)
            arr.add(i);
        }
        return arr;
	}
	public static HashSet<Integer> primeSet(int n)
	{
	    HashSet<Integer> arr=new HashSet<>();
	    boolean prime[] = new boolean[n + 1];
        for (int i = 0; i <= n; i++)
        prime[i] = true;
        for (int p = 2; p * p <= n; p++)
        {
            if (prime[p] == true)
            {
                for (int i = p * p; i <= n; i += p)
                prime[i] = false;
            }
        }
        for (int i = 2; i <= n; i++)
        {
            if (prime[i] == true)
            arr.add(i);
        }
        return arr;
	}

	// Fenwick / BinaryIndexed  Tree  USE IT - FenwickTree ft1=new FenwickTree(n);
	public static class FenwickTree
	{
		long farr[];
		int n;
		public FenwickTree(int c)
		{
			n=c+1;
			farr=new long[n];
		}
		public void update_range(int l,int r,long p)
		{
			update(l,p);
			update(r+1,(-1)*p);
		}
		public void update(int x,long p)
		{
			for(;x<n;x+=x&(-x))
			{
				farr[x]+=p;
			}
		}
		public long get(int x)
		{
			long ans=0;
			for(;x>0;x-=x&(-x))
			{
				ans=ans+farr[x];
			}
			return ans;
		}
	}

	//Disjoint Set Union
	public static class DSU
	{
	    static int par[],rank[];
	    public DSU(int c)
	    {
	        par=new int[c+1];
	        rank=new int[c+1];
	        for(int i=0;i<=c;i++)
	        {
	            par[i]=i;
	            rank[i]=0;
	        }
	    }
	    public static int find(int a)
	    {
	        if(a==par[a])
	        return a;
	        return par[a]=find(par[a]);
	    }
	    public static void union(int a,int b)
	    {
	        int a_rep=find(a),b_rep=find(b);
	        if(a_rep==b_rep)
	        return;
	        if(rank[a_rep]<rank[b_rep])
	        par[a_rep]=b_rep;
	        else if(rank[a_rep]>rank[b_rep])
	        par[b_rep]=a_rep;
	        else
	        {
	            par[b_rep]=a_rep;
	            rank[a_rep]++;
	        }
	    }
	}

	//SEGMENT TREE CODE

	// public static void segmentUpdate(int si,int ss,int se,int qs,int qe,long x)
	// {
	// 	if(ss>qe || se<qs)return;
	// 	if(qs<=ss && qe>=se)
	// 	{
	// 		seg[si][0]+=1L;
	// 		seg[si][1]+=x*x;
	// 		seg[si][2]+=2*x;
	// 		return;
	// 	}
	// 	int mid=(ss+se)/2;
	// 	segmentUpdate(2*si+1,ss,mid,qs,qe,x);
	// 	segmentUpdate(2*si+2,mid+1,se,qs,qe,x);
	// }
	// public static long segmentGet(int si,int ss,int se,int x,long f,long s,long t,long a[])
	// {
	// 	if(ss==se && ss==x)
	// 	{
	// 		f+=seg[si][0];
	// 		s+=seg[si][1];
	// 		t+=seg[si][2];
	// 		long ans=a[x]+(f*((long)x+1L)*((long)x+1L))+s+(t*((long)x+1L));
	// 		return ans;
	// 	}
	// 	int mid=(ss+se)/2;
	// 	if(x>mid){
	// 		return segmentGet(2*si+2,mid+1,se,x,f+seg[si][0],s+seg[si][1],t+seg[si][2],a);
	// 	}else{
	// 		return segmentGet(2*si+1,ss,mid,x,f+seg[si][0],s+seg[si][1],t+seg[si][2],a);
	// 	}
	// }

	public static class pair
    {
    	long a;
    	long b;
    	public pair(long val,long index)
    	{
    	    a=val;
    	    b=index;
    	}
    }
	public static class myComp implements Comparator<pair>
	{
		//sort in ascending order.
		public int compare(pair p1,pair p2)
		{
			if(p1.a==p2.a)
    	    return 0;
    	    else if(p1.a<p2.a)
    	    return -1;
    	    else
    	    return 1;
		}
		//sort in descending order.
		// public int compare(pair p1,pair p2)
    	// {
    	//     if(p1.a==p2.a)
    	//     return 0;
    	//     else if(p1.a<p2.a)
    	//     return 1;
    	//     else
    	//     return -1;
    	// }
	}
    public static class myComp1 implements Comparator<pair1>
    {
		//sort in ascending order.
    	public int compare(pair1 p1,pair1 p2)
    	{
    	    if(p1.a==p2.a)
    	    return 0;
    	    else if(p1.a<p2.a)
    	    return -1;
    	    else
    	    return 1;
    	}
		//sort in descending order.
		// public int compare(pair p1,pair p2)
    	// {
    	//     if(p1.a==p2.a)
    	//     return 0;
    	//     else if(p1.a<p2.a)
    	//     return 1;
    	//     else
    	//     return -1;
    	// }
    }
	public static class pair1
    {
    	long a;
    	long b;
    	public pair1(long val,long index)
    	{
    	    a=val;
    	    b=index;
    	}
    }
    public static ArrayList<pair1> mergeIntervals(ArrayList<pair1> arr)
	{
	    //****************use this in main function-Collections.sort(arr,new myComp1());
	    ArrayList<pair1> a1=new ArrayList<>();
	    if(arr.size()<=1)
	    return arr;
	    a1.add(arr.get(0));
	    int i=1,j=0;
	    while(i<arr.size())
	    {
	        if(a1.get(j).b<arr.get(i).a)
	        {
	           a1.add(arr.get(i));
	           i++;
	           j++;
	        }
	        else if(a1.get(j).b>arr.get(i).a && a1.get(j).b>=arr.get(i).b)
	        {
	            i++;
	        }
	        else if(a1.get(j).b>=arr.get(i).a)
	        {
	            long a=a1.get(j).a;
	            long b=arr.get(i).b;
	            a1.remove(j);
	            a1.add(new pair1(a,b));
	            i++;
	        }
	    }
	    return a1;
	}
	public static boolean palindrome(String s,int n)
	{
		for(int i=0;i<=n/2;i++){
			if(s.charAt(i)!=s.charAt(n-i-1)){
				return false;
			}
		}
		return true;
	}
	public static long countDigit(long n)
	{
	    long sum=0;
	    while(n!=0)
	    {
	        sum++;
	        n=n/10;
	    }
	    return sum;
	}
	public static long digitSum(long n)
	{
	    long sum=0;
	    while(n!=0)
	    {
	        sum=sum+n%10;
	        n=n/10;
	    }
	    return sum;
	}
	public static long gcd(long a,long b)
	{
	    if(b==0)
	    return a;
	    else
	    return gcd(b,a%b);
	}
	public static int gcd(int a,int b)
	{
	    if(b==0)
	    return a;
	    else
	    return gcd(b,a%b);
	}
	public static long pwr(long m,long n)
	{
		long res=1;
		m=m%mod;
		if(m==0)
		return 0;
		while(n>0)
		{
			if((n&1)!=0)
			{
				res=(res*m)%mod;
			}
			n=n>>1;
			m=(m*m)%mod;
		}
		return res;
	}
	public static void sort(int[] A)
	{
        int n = A.length;
        Random rnd = new Random();
        for(int i=0; i<n; ++i)
		{
            int tmp = A[i];
            int randomPos = i + rnd.nextInt(n-i);
            A[i] = A[randomPos];
            A[randomPos] = tmp;
        }
        Arrays.sort(A);
    }
    public static void sort(long[] A)
	{
	    int n = A.length;
        Random rnd = new Random();
        for(int i=0; i<n; ++i)
		{
            long tmp = A[i];
            int randomPos = i + rnd.nextInt(n-i);
            A[i] = A[randomPos];
            A[randomPos] = tmp;
        }
	    Arrays.sort(A);
	}
	public static int I(){return sc.I();}
    public static long L(){return sc.L();}
    public static String S(){return sc.S();}
    public static double D(){return sc.D();}
}
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 I(){ 
        return Integer.parseInt(next());
    }
    long L(){ 
        return Long.parseLong(next());
    }
    double D(){
         return Double.parseDouble(next());
    }
    String S(){
        String str = "";
        try 
        {
            str = br.readLine();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        return str;
    }
}