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.
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Vector;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author xwchen
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskD solver = new TaskD();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskD {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int T = in.nextInt();
            while (T-- > 0) {
                int n = in.nextInt();
                char[] a = in.nextLine().toCharArray();
                char[] b = in.nextLine().toCharArray();
                Vector<Integer> res = new Vector<>();
                int left = 1;
                int right = n - 1;
                for (int i = 0; i < n; ++i) {
                    int j = n - i - 1;
                    int next;
                    if (i % 2 == 1) {
                        next = left++;
                    } else {
                        next = right--;
                    }
                    if (j == 0) {
                        if (a[0] != b[0]) {
                            res.add(1);
                            break;
                        }
                    }
                    if (a[0] == b[j]) {
                        res.add(1);
                        invert(a, 0);
                    }
                    res.add(j + 1);
                    a[0] = a[next];
                    if (i % 2 == 0) {
                        invert(a, 0);
                    }
                }
                out.print(res.size() + " ");
                for (int i = 0; i < res.size(); ++i) {
                    out.print(res.get(i) + " ");
                }
                out.println();
            }
        }

        void invert(char[] s, int pos) {
            if (s[pos] == '1') s[pos] = '0';
            else s[pos] = '1';
        }

    }

    static class InputReader {
        private BufferedReader reader;
        private StringTokenizer tokenizer = new StringTokenizer("");

        public InputReader(InputStream inputStream) {
            this.reader = new BufferedReader(
                    new InputStreamReader(inputStream));
        }

        public String next() {
            while (!tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return tokenizer.nextToken();
        }

        public String nextLine() {
            String ret = "";
            try {
                ret = reader.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return ret;
        }

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

    }
}

