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.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.StringTokenizer;
import java.util.TreeMap;


public class COVID {

	static ArrayList<Integer>[] adjList;

	static int mod;
static int INF=(int)1e6;



public static void perfrom(char[] arr, int idx) {
	for(int i=0;i<idx;i++) {
		arr[i]^='0'^'1';
	}
	int i=0;int j=idx-1;
	while(i<j) {
		char tmp=arr[i];
		arr[i]=arr[j];
		arr[j]=tmp;
		i++;
		j--;
	}
	
}

public static void main(String[] args) throws Exception {

		Scanner	sc = new Scanner(System.in);
		PrintWriter pw= new PrintWriter(System.out);
		int t=sc.nextInt();
	h:	while(t-->0) {
		int n=sc.nextInt();
		char[] a=sc.next().toCharArray();
		char[] b=sc.next().toCharArray();
		int cura=0;
		int curb=n-1;
		ArrayList<Integer> ans=new ArrayList<>();
		while(curb>=0) {
			if(a[cura]!=b[curb]) {
				ans.add(curb+1);
				perfrom(a, curb+1);
				
			}else {
				ans.add(cura+1);
				perfrom(a, 1);
				ans.add(curb+1);
				perfrom(a, curb+1);
			}
			curb--;
		}
		pw.print(ans.size()+" ");
		for(int num:ans)
			pw.print(num+" ");
	pw.println();
		
	}
		pw.close();

	}

	


	static long gcd(long a, long b) {
		return (b==0)?a:gcd(b,a%b);
	}
	static long lcm(long a, long b) {
		return a/gcd(a,b)*b;
	}
	public static int log(int n , int base) {
		int ans=0;
		while(n+1>base) {
			ans++;
			n/=base;
		}
		return ans;
	}
	static int pow(int b,long e) {
		int ans=1;
		while(e>0) {
			if((e&1)==1)
				ans=(int)((ans*1l*b));
			e>>=1;{

			}
			b=(int)((b*1l*b));
		}
		return ans;
	}
	static long powmod(long b,long e, int mod) {
		long ans=1;
		b%=mod;
		while(e>0) {
			if((e&1)==1)
				ans=(int)((ans*1l*b)%mod);
			e>>=1;
			b=(int)((b*1l*b)%mod);
		}
		return ans;
	}
	public static long add(long a, long b) {
		return (a+b)%mod;
	}
	public static long mul(long a, long b) {
		return ((a%mod)*(b%mod))%mod;
	}







	
static class Pair implements Comparable<Pair>{

		int  x;int y;



		public Pair(int a,int b) {
			this.x=a;y=b;
		}









		public int compareTo(Pair o) {
			return (x==o.x)?((y>o.y)?1:(y==o.y)?0:-1):((x>o.x)?1:-1);
			//		return y-o.y;
		}


		@Override




		public int hashCode() {
			final int prime = 31;
			int result = 1;
			result = prime * result + x;
			result = prime * result + y;
			return result;
		}


		@Override


		public boolean equals(Object obj) {
			if (this == obj)
				return true;
			if (obj == null)
				return false;
			if (getClass() != obj.getClass())
				return false;
			Pair other = (Pair) obj;
			if (x != other.x)
				return false;
			if (y != other.y)
				return false;
			return true;
		}

	}







	static class Scanner {
		StringTokenizer st;
		BufferedReader br;

		public Scanner(InputStream s) {
			br = new BufferedReader(new InputStreamReader(s));
		}
		public Scanner(String s) throws FileNotFoundException{	br = new BufferedReader(new FileReader(s));}

		public long[] nextLongArr(int n) throws IOException {
			long[] arr=new long[n];
			for(int i=0;i<n;i++)
				arr[i]=nextLong();
			return arr;
		}
		public int[] nextIntArr(int n) throws IOException {
			int[] arr=new int[n];
			for(int i=0;i<n;i++)
				arr[i]=nextInt();
			return arr;
		}
		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine()," ,");
			return st.nextToken();
		}

		public int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		public long nextLong() throws IOException {
			return Long.parseLong(next());
		}

		public String nextLine() throws IOException {
			return br.readLine();
		}


		public double nextDouble() throws IOException {
			String x = next();
			StringBuilder sb = new StringBuilder("0");
			double res = 0, f = 1;
			boolean dec = false, neg = false;
			int start = 0;
			if (x.charAt(0) == '-') {
				neg = true;
				start++;
			}
			for (int i = start; i < x.length(); i++) {
				if (x.charAt(i) == '.') {
					res = Long.parseLong(sb.toString());
					sb = new StringBuilder("0");
					dec = true;
				} else {
					sb.append(x.charAt(i));
					if (dec)
						f *= 10;
				}
				if (sb.length() == 18) {
					res += Long.parseLong(sb.toString()) / f;
					sb = new StringBuilder("0");
				}
			}
			res += Long.parseLong(sb.toString()) / f;
			return res * (neg ? -1 : 1);
		}

		public boolean ready() throws IOException {
			return br.ready();
		}

	}

	public static void shuffle(int[] a) {
		int n = a.length;
		for (int i = 0; i < n; i++) {
			int r = i + (int) (Math.random() * (n - i));
			int tmp = a[i];
			a[i] = a[r];
			a[r] = tmp;
		}
	}
}