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.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Random;
import java.util.StringTokenizer;

public class PrefFlip {
	
	static final int MAXN = 1000_006;
	
	static final long MOD = (long) 1e9 + 7;
	
	public static void main(String[] args) throws IOException {
		MyScanner s = new MyScanner();
		Print p = new Print();
		int t = s.nextInt();
		
		while (t-- > 0) {
			int n = s.nextInt();
			String str1 = s.nextLine();
			String str2 = s.nextLine();
			str1 += "0";
			str2 += "0";
			ArrayList<Integer> sol1 = new ArrayList<>();
			ArrayList<Integer> sol2 = new ArrayList<>();
			for (int i = 1; i <= n; i++) {
				if (str1.charAt(i) != str1.charAt(i - 1))
					sol1.add(i);
				if (str2.charAt(i) != str2.charAt(i - 1))
					sol2.add(i);
				
			}
			Collections.reverse(sol2);
			sol1.addAll(sol2);
			p.print(sol1.size());
			for (int num : sol1)
				p.print(" " + num);
			p.println("");
		}
		p.close();
	}
	
	public static class Pair implements Comparable<Pair> {
		
		int first;
		
		int second;
		
		public Pair(int a, int b) {
			this.first = a;
			this.second = b;
		}
		
		@Override
		public int hashCode() {
			final int prime = 31;
			int result = 1;
			result = prime * result + first;
			result = prime * result + second;
			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 (first != other.first)
				return false;
			if (second != other.second)
				return false;
			return true;
		}
		
		@Override
		public int compareTo(Pair o) {
			// TODO Auto-generated method stub
			return o.first - first;
		}
		
	}
	
	public static class Helper {
		
		long MOD = (long) 1e9 + 7;
		
		int MAXN = 1000_006;;
		
		Random rnd;
		
		public Helper(long mod, int maxn) {
			MOD = mod;
			MAXN = maxn;
			rnd = new Random();
		}
		
		public Helper() {
			
		}
		
		public static int[] sieve;
		
		public static ArrayList<Integer> primes;
		
		public void setSieve() {
			primes = new ArrayList<>();
			sieve = new int[MAXN];
			int i, j;
			for (i = 2; i < MAXN; ++i)
				if (sieve[i] == 0) {
					primes.add(i);
					for (j = i; j < MAXN; j += i) {
						sieve[j] = i;
					}
				}
		}
		
		public static long[] factorial;
		
		public void setFactorial() {
			factorial = new long[MAXN];
			factorial[0] = 1;
			for (int i = 1; i < MAXN; ++i)
				factorial[i] = factorial[i - 1] * i % MOD;
		}
		
		public long getFactorial(int n) {
			if (factorial == null)
				setFactorial();
			return factorial[n];
		}
		
		public long ncr(int n, int r) {
			if (r > n)
				return 0;
			if (factorial == null)
				setFactorial();
			long numerator = factorial[n];
			long denominator = factorial[r] * factorial[n - r] % MOD;
			return numerator * pow(denominator, MOD - 2, MOD) % MOD;
		}
		
		public long[] getLongArray(int size, MyScanner s) throws Exception {
			long[] ar = new long[size];
			for (int i = 0; i < size; ++i)
				ar[i] = s.nextLong();
			return ar;
		}
		
		public int[] getIntArray(int size, MyScanner s) throws Exception {
			int[] ar = new int[size];
			for (int i = 0; i < size; ++i)
				ar[i] = s.nextInt();
			return ar;
		}
		
		public int[] getIntArray(String s) throws Exception {
			s = s.trim().replaceAll("\\s+", " ");
			String[] strs = s.split(" ");
			int[] arr = new int[strs.length];
			for (int i = 0; i < strs.length; i++) {
				arr[i] = Integer.parseInt(strs[i]);
			}
			return arr;
		}
		
		public long gcd(long a, long b) {
			return b == 0 ? a : gcd(b, a % b);
		}
		
		public int gcd(int a, int b) {
			return b == 0 ? a : gcd(b, a % b);
		}
		
		public long max(long[] ar) {
			long ret = ar[0];
			for (long itr : ar)
				ret = Math.max(ret, itr);
			return ret;
		}
		
		public int max(int[] ar) {
			int ret = ar[0];
			for (int itr : ar)
				ret = Math.max(ret, itr);
			return ret;
		}
		
		public long min(long[] ar) {
			long ret = ar[0];
			for (long itr : ar)
				ret = Math.min(ret, itr);
			return ret;
		}
		
		public int min(int[] ar) {
			int ret = ar[0];
			for (int itr : ar)
				ret = Math.min(ret, itr);
			return ret;
		}
		
		public long sum(long[] ar) {
			long sum = 0;
			for (long itr : ar)
				sum += itr;
			return sum;
		}
		
		public long sum(int[] ar) {
			long sum = 0;
			for (int itr : ar)
				sum += itr;
			return sum;
		}
		
		public long pow(long base, long exp, long MOD) {
			base %= MOD;
			long ret = 1;
			while (exp > 0) {
				if ((exp & 1) == 1)
					ret = ret * base % MOD;
				base = base * base % MOD;
				exp >>= 1;
			}
			return ret;
		}
		
	}
	
	static class Print {
		
		private BufferedWriter bw;
		
		public Print() {
			this.bw = new BufferedWriter(new OutputStreamWriter(System.out));
		}
		
		public void print(Object object) throws IOException {
			bw.append("" + object);
		}
		
		public void println(Object object) throws IOException {
			print(object);
			bw.append("\n");
		}
		
		public void close() throws IOException {
			bw.close();
		}
	}
	
	public static class MyScanner {
		
		BufferedReader br;
		
		StringTokenizer st;
		
		public MyScanner() {
			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;
		}
	}
	
}