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.
// Main Code at the Bottom
import java.util.*;
import java.lang.*;
import java.io.*;
import java.math.BigInteger; 
public class Main{
	//Fast IO class
    static class FastReader {
        BufferedReader br; 
        StringTokenizer st; 
        public FastReader() {
        	boolean env=System.getProperty("ONLINE_JUDGE") != null;
        	if(!env) {
        		try {
					br=new BufferedReader(new FileReader("src\\input.txt"));
				} catch (FileNotFoundException e) {
					e.printStackTrace();
				}
        	}
        	else 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 nextInt() {
            return Integer.parseInt(next()); 
        } 
        long nextLong() {
            return Long.parseLong(next()); 
        } 
        double nextDouble() {
            return Double.parseDouble(next()); 
        } 
        String nextLine() {
            String str = ""; 
            try {
                str = br.readLine(); 
            } 
            catch (IOException e) {
                e.printStackTrace(); 
            } 
            return str; 
        } 
    }     
    static long MOD=1000000000+7;
    //debug
    static void debug(Object... o) {
        System.out.println(Arrays.deepToString(o));
    }
    // Pair
    static class pair{
    	long x,y;
    	pair(long a,long b){
    		this.x=a;
    		this.y=b;
    	}
    	public boolean equals(Object obj) {
    		if(obj == null || obj.getClass()!= this.getClass()) return false;
            pair p = (pair) obj;
            return (this.x==p.x && this.y==p.y);
        }
    	public int hashCode() {
            return Objects.hash(x,y);
        }
    }
    static FastReader sc=new FastReader();
    static PrintWriter out=new PrintWriter(System.out);  
    //Global variables and functions
    //Main function(The main code starts from here)
    static void op(int x,char s[]) {
    	for(int i=0;i<x;i++) {
    		if(s[i]=='0') s[i]='1';
    		else s[i]='0';
    	}
    	int l=0,r=x-1;
    	while(l<r) {
    		char tmp=s[l];
    		s[l]=s[r];
    		s[r]=tmp;
    		l++;
    		r--;
    	}
    }
    public static void main (String[] args) throws java.lang.Exception {
    	int test=1;
    	test=sc.nextInt();
    	while(test-->0){
    		int n=sc.nextInt();
    		char s[]=sc.nextLine().toCharArray(),t[]=sc.nextLine().toCharArray();
    		ArrayList<Integer> ans=new ArrayList<>();
    		int pre=0,suf=n-1;
    		for(int i=n-1;i>=0;i--) {
    			if(t[i]==s[suf]) {
    				suf--;
    				continue;
    			}
    			int j=i;
    			char c=t[i];
    			while(j>=0 && t[j]==s[pre] && t[j]==c) {
    				j--;
    				pre++;
    			}
    			
    			if(i-j>=1) ans.add(i-j);
    			ans.add(i+1);
    			if(j>=0 && pre<n && t[j]!=s[pre]) {
    				pre++;
    				if(j>0) ans.add(j);
    				i=j;
    			}
    			else {
    				ans.add(j+1);
    				i=j+1;
    			}
    		}
    		out.print(ans.size()+" ");
    		for(Integer x: ans) out.print(x+" ");
    		out.println();
    	}	
        out.flush();
        out.close();
    }
}