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.
/* package codechef; // don't place package name! */

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

/* Name of the class has to be "Main" only if the class is public. */
public class Codechef
{   
	public static void main (String[] args) throws java.lang.Exception
	{  FastReader in = new FastReader(System.in);
        StringBuilder sb = new StringBuilder();
        int tt=1;
        tt=in.nextInt();
        while(tt>0){
            --tt;
            int n=in.nextInt();
            String s=in.next();
            String t=in.next();
            s+='0';
            t+='0';
            List<Integer> list=new ArrayList<Integer>();
            for(int i=0;i<n;i++)
            {
              if(s.charAt(i)!=s.charAt(i+1))
              {
                  list.add(i+1);
              }
              
            }
            for(int i=n-1;i>=0;i--)
            {
                if(t.charAt(i)!=t.charAt(i+1))
                 list.add(i+1);
            }
            sb.append(Integer.toString(list.size())+" ");
            for(int i=0;i<list.size();i++)
              sb.append(Integer.toString(list.get(i))+" ");
            sb.append("\n");  
        }
	    System.out.print(sb);
	}
	
    static int upper_bound(int arr[],int x){
	    int a=Arrays.binarySearch(arr,x);
	    if(a<0){
	        a*=(-1);
	    
	        return a-1; 
	    }
	    else{
	        
	        while(a<arr.length && arr[a]==x)
	           ++a;
	           return a;
	    }
	}
	static long gcd(long a ,long b)
	{
    if(a==0)
    return b;
    else return gcd(b%a,a);
    }
    
//------making a Fendwick tree ---//
	// creating a fendwick tree
	static long ftree[];
	static void buildFendwicktree(int arr[],int n)
	{
		ftree=new long[n+1];
		for(int i=0;i<n;i++)
			upftree(arr[i],i,n);
	}
	static void upftree(int value,int n,int i)
	{
		int index=i+1;
		while(index<=n)
		{
		  ftree[index]+=value;
		  index+=(index&(-index));  // adding last bit to the index 
		}
	}
	static long getSum(int index)
	{
		long sum=0;
		index+=1;
		while(index>0)
		{
			sum+=ftree[index];
			index-=(index&(-index)); // fliping last index of the tree; 
		}
		return sum;
	}
//------Fendwick tree ends ---------//
}


class sgmtree{
    int arr[];
    sgmtree(int input[],int n){
        arr=new int[100001];
        buildtree(input,1,0,n-1);
    }
    void buildtree(int input[],int si,int ss,int se){
        if(ss==se){
         arr[si]=input[ss];
         return;
        }
         int mid=(ss+se)/2;
         buildtree(input,2*si,ss,mid);
         buildtree(input,2*si+1,mid+1,se);
         arr[si]=Math.min(arr[2*si],arr[2*si+1]);
         
    }
    int query(int si,int ss,int se,int qs,int qe){
        if(qs>se  || qe<ss)
         return Integer.MAX_VALUE;
        
        if(ss>=qs && qe>=se)
        return arr[si];
        
        int mid=(ss+se)/2;
        int l=query(2*si,ss,mid,qs,qe);
        int r=query(2*si+1,mid+1,se,qs,qe);
        return Math.min(l,r);
    }
    void update(int input[],int index,int value){
        input[index]=value;
        updateutils(input,1,0,input.length-1,index);
    }
    void updateutils(int input[],int si,int ss,int se,int qi){
        if(ss==se){
            arr[si]=input[ss];
            return;
        }
        int mid=(ss+se)/2;
        if(qi<=mid)
        updateutils(input,2*si,ss,mid,qi);
        else
        updateutils(input,2*si+1,mid+1,se,qi);
        arr[si]=Math.min(arr[2*si],arr[2*si+1]);
    }
    
}
	
	/* This is for sorting first accorting to gain[1] if gain[1] is same the gain[0]
Arrays.sort(gain, (long[] l1, long[] l2) -> {
	        if(l1[1] != l2[1])return Long.compare(l2[1], l1[1]);//Sorting in non-increasing order of gain
	        return Long.compare(l1[0], l2[0]);//Choosing smallest bit among all bits having same gain
	    });
*/

class pair{
    int x,y;
    pair(int x,int y){
        this.x=x;
        this.y=y;
    }
}	
class CompareValue { 
  
    static void compare(pair arr[], int n) 
    { 
        Arrays.sort(arr, new Comparator<pair>() { 
        public int compare(pair p1, pair p2) 
            { 
                return p1.y - p2.y; 
            } 
        }); 
    } 
}
class CompareKey{
    static void compare(pair arr[],int n){
        Arrays.sort(arr,new Comparator<pair>(){
            public int compare(pair p1,pair p2)
            {
                return p2.x-p1.x;
            }
        });
    }
}
class FastReader {

    byte[] buf = new byte[2048];
    int index, total;
    InputStream in;

    FastReader(InputStream is) {
        in = is;
    }

    int scan() throws IOException {
        if (index >= total) {
            index = 0;
            total = in.read(buf);
            if (total <= 0) {
                return -1;
            }
        }
        return buf[index++];
    }

    String next() throws IOException {
        int c;
        for (c = scan(); c <= 32; c = scan()) ;
        StringBuilder sb = new StringBuilder();
        for (; c > 32; c = scan()) {
            sb.append((char) c);
        }
        return sb.toString();
    }

    String nextLine() throws IOException {
        int c;
        for (c = scan(); c <= 32; c = scan()) ;
        StringBuilder sb = new StringBuilder();
        for (; c != 10 && c != 13; c = scan()) {
            sb.append((char) c);
        }
        return sb.toString();
    }

    char nextChar() throws IOException {
        int c;
        for (c = scan(); c <= 32; c = scan()) ;
        return (char) c;
    }

    int nextInt() throws IOException {
        int c, val = 0;
        for (c = scan(); c <= 32; c = scan()) ;
        boolean neg = c == '-';
        if (c == '-' || c == '+') {
            c = scan();
        }
        for (; c >= '0' && c <= '9'; c = scan()) {
            val = (val << 3) + (val << 1) + (c & 15);
        }
        return neg ? -val : val;
    }

    long nextLong() throws IOException {
        int c;
        long val = 0;
        for (c = scan(); c <= 32; c = scan()) ;
        boolean neg = c == '-';
        if (c == '-' || c == '+') {
            c = scan();
        }
        for (; c >= '0' && c <= '9'; c = scan()) {
            val = (val << 3) + (val << 1) + (c & 15);
        }
        return neg ? -val : val;
    }
}	