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

public class Main{
	static BufferedReader reader;
	static StringTokenizer tokenizer;
	static PrintWriter writer;

	static int nextInt() throws IOException {
		return Integer.parseInt(nextToken());
	}

	static long nextLong() throws IOException {
		return Long.parseLong(nextToken());
	}

	static double nextDouble() throws IOException {
		return Double.parseDouble(nextToken());
	}

	static String nextToken() throws IOException {
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			tokenizer = new StringTokenizer(reader.readLine());
		}
		return tokenizer.nextToken();
	}
	static String nexts() throws IOException {
	  	  tokenizer = new StringTokenizer(reader.readLine());
	   	 String s="";
	   	 while (tokenizer.hasMoreTokens()) {
			s+=tokenizer.nextElement()+" ";
		}
		return s;
	}
	public static int gcd(int x, int y){
		if (y == 0) return x; else return gcd(y, x % y);
	}

	public static boolean isPrime(int nn) 
	    { 
	         if(nn<=1){
		 return false; }
	        if(nn<=3){
		 return true; }
	      if (nn%2==0||nn%3==0){
		 return false; }
	        for (int i=5;i*i<=nn;i=i+6){ 
	            if(nn%i==0||nn%(i+2)==0){
	            	return false;  }
	            }
	         return true; 
	    } 

	public static void shuffle(int[] A) {
		for (int i = 0; i < A.length; i++) {
			int j = (int)(i * Math.random());
			int tmp = A[i];
			A[i] = A[j];
			A[j] = tmp;
		}
	}
	public static void shufflel(Long[] A) {
		for (int i = 0; i < A.length; i++) {
			int j = (int)(i * Math.random());
			long tmp = A[i];
			A[i] = A[j];
			A[j] = tmp;
		}
	}

	public static String reverse(String input)
 	   {
	        StringBuilder input2=new StringBuilder();
	        input2.append(input);
	        input2 = input2.reverse();
	        return input2.toString();
	    }


	 public static long power(int x, long n)
	{
	//    long mod = 1000000007;
		if (n == 0) {
			return 1;
		}

		long pow = power(x, n / 2);

		if ((n & 1) == 1) {
			return (x * pow * pow);
		}
		return (pow * pow);
	}
	public static long power(long x, long y, long p)     //x^y%p
	    { 
  	       long res = 1; 
	       x = x % p; 
  	       while (y > 0) { 
 	 	 if (y % 2 == 1) {
      	        	        res = (res * x) % p; 
		 }
  		 y = y >> 1; // y = y/2 
     	     	 x = (x * x) % p; 
     	         } 
  	         return res; 
    	} 

	 static long ncr(int n, int k)  
   	 { 
           		 long res = 1; 
  		   // Since C(n, k) = C(n, n-k)  
 		       if (k > n - k) { 
     		       k = n - k; 
      		  } 
  		  // Calculate value of [n*(n-1)*---*(n-k+1)] / [k*(k-1)*---*1]  
     		   for (int i = 0; i < k; ++i) { 
        		    res *= (n - i); 
         		   res /= (i + 1); 
     		   } 
  		  return res; 
 	   }
	public static int inv(int a, int m)     //Returns modulo inverse of a with respect to m using extended euclid algorithm
	    { 
	        int m0=m,t,q; 
	        int x0=0,x1=1; 
      	        if(m==1){
	                return 0; }
                 	         while(a>1) 
     	        {  
   	                q=a/m; 
    	                t=m; 
                                 m=a%m;a=t; 
    	                t=x0; 
     	                x0=x1-q*x0; 
      	                x1=t; } 
    	          if(x1<0){
 	   	 x1+=m0; }
   	           return x1; 
	    } 

	static int modInverse(int n, int p) 
  	{ 
    	          return (int)power((long)n, (long)(p - 2),(long)p); 
	 } 
	static int ncrmod(int n, int r, int p) 
   	 { 
	        if (r == 0)        // Base case 
	            return 1; 
  	        int[] fac = new int[n + 1];         // Fill factorial array so that we can find all factorial of r, n and n-r 
	        fac[0] = 1; 
	        for (int i = 1; i <= n; i++) 
                                     fac[i] = fac[i - 1] * i % p; 
   	         return (fac[n] * modInverse(fac[r], p) % p * modInverse(fac[n - r], p) % p) % p;     //IMPORTANT
    	}	 

	static int upper(int a[], int x)   //Returns rightest index of x in sorted arr else -1
  	  {                                                //If not present returns index of just smaller element
  	            int n=a.length;
    	        int l=0;
                int r=n-1;
                int ans=-1;
                while(l<=r){
                    int m=(r-l)/2+l;
                    if(a[m]<=x){
                        ans=m;
                        l=m+1;
                    }
                    else{
                        r=m-1;
                    }
                }
                 return ans;  
                } 
	static int lower(int a[], int x)     //Returns leftest index of x in sorted arr else n
 	   {                                                  //If not present returns index of just greater element
 	            int n=a.length;
   	            int l=0;
                int r=n-1;
                int ans=n;
                while(l<=r){
                    int m=(r-l)/2+l;
                    if(a[m]>=x){
                        ans=m;
                        r=m-1;
                    }
                    else{
                         l=m+1;
                    }
                }
                 return ans; 
                 } 

	public static long stringtoint(String s){ // Convert bit string to number
		long a = 1;
		long ans = 0;
		StringBuilder sb = new StringBuilder();
		sb.append(s);  
		sb.reverse();
		s=sb.toString();
		for(int i=0;i<s.length();i++){
			ans = ans + a*(s.charAt(i)-'0');
			a = a*2;
		}
		return ans;
	}
 
	String inttostring(long a,long m){        // a is number and m is length of string required
		String res = "";                     // Convert a number in bit string representation
		for(int i=0;i<(int)m;i++){
			if((a&(1<<i))==1){
				res+='1';
			}else
				res+='0';
		}
		StringBuilder sb = new StringBuilder();
		sb.append(res);  
		sb.reverse();
		res=sb.toString();
		return res;
    }
	
	 static class R implements Comparable<R>{
	        int x, y;
	        public  R(int x, int y) {           //a[i]=new R(x,y);
	            this.x = x;
	            this.y = y;
	        }
	        public int compareTo(R o) {
            		return x-o.x;     //Increasing order(Which is usually required)
        		}
	    }   
/*   FUNCTION TO SORT HASHMAP ACCORDING TO VALUE
//USE IT AS FOLLOW	

//Make a new list
List<Map.Entry<Integer, Integer> > list = 
               new LinkedList<Map.Entry<Integer, Integer> >(h.entrySet()); 
  
        // Sort the list 
        Collections.sort(list, new Comparator<Map.Entry<Integer, Integer> >() { 
            public int compare(Map.Entry<Integer, Integer> o1,  
                               Map.Entry<Integer, Integer> o2) 
            { 
                return (o1.getValue()).compareTo(o2.getValue());     //This is used to sort string stored as VALUE, use below function here accordingly
            } 
        }); 
          
        // put data from sorted list to new hashmap  
        HashMap<String, Integer> temp = new LinkedHashMap<String, Integer>(); 
        for (Map.Entry<String, Integer> aa : list) { 
            temp.put(aa.getKey(), aa.getValue()); 
        } 
        return temp;   //Now temp is our new sorted hashmap
OR
	for(int i = 0;i<h.size();i++)  //accessing elements from the list made
		{
			int count = list.get(i).getValue();    //Value
			while(count >= 0)
			{
					int key=list.get(i).getKey();  //key
					count -- ;
			}
		}

////////////////////////////////////////////////////////////////////////////////////////
public int compare(Entry<Integer, Integer> o1, Entry<Integer, Integer> o2) 
	{
		if(o1.getValue() != o2.getValue())
			return o1.getValue() > o2.getValue()?1:-1;  //Sorts Value in increasing order
		else if(o1.getValue() == o2.getValue()){
			return o1.getKey() > o2.getKey() ? 1:-1;  //If value equal, then sorts key in increasing order
		}
		
		return Integer.MIN_VALUE;
	}
*/
//Check if palindrome string - System.out.print(A.equals(new StringBuilder(A).reverse().toString())?"Yes":"No");
	public static void main(String[] args) throws IOException {
		reader = new BufferedReader(new InputStreamReader(System.in));
		tokenizer = null;
		writer = new PrintWriter(System.out);
		solve();
		reader.close();
		writer.close();
	}
	
	private static void solve() throws IOException {
		int t = nextInt();
		while(t-->0){
			//String s= nextToken();
			//String[] s = str.split("\\s+");
			ArrayList<Integer> ans=new ArrayList<Integer>();
			//HashSet<Integer> set=new HashSet<Integer>();
			//HashMap<Integer,String> h=new HashMap<Integer,String>();
			//R[] a1=new R[n];
			
			//PriorityQueue<Integer> pq=new PriorityQueue<Integer>(Collections.reverseOrder());
			//NavigableSet<Integer> pq=new TreeSet<>();
			int n = nextInt();
			//long n = nextLong();

			char[] a=nextToken().toCharArray();
			char[] b=nextToken().toCharArray();
			//long[] a=new long[n];
			
			//shuffle(a);
			//shufflel(a);
			//Arrays.sort(a);
			for(int i=n-1;i>=0;i--){
			    if(a[i]!=b[i]){
			        ans.add(i+1);
                    ans.add(1);
                    ans.add(i+1);
			    }
			}
            writer.print(ans.size()+" ");
            for(int p:ans)writer.print(p+" ");
            writer.println();
			
		 }
	}
}