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.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.*;
import java.util.stream.Collectors;

public class Main {

    public static void main(String[] args) {
        Problems problems = new Problems();
        problems.solve();
    }
}

class Problems {

    Parser parser = new Parser();

    void solve() {
        int t = parser.parseInt();
        for (int i = 0; i < t; i++) {
            Problem problem = new Problem();
            problem.solve();
        }
    }

    class Problem {

        void solve() {
            int n = parser.parseInt();
            String a = parser.parseString();
            String b = parser.parseString();

            int l = 0;
            int r = n - 1;
            int curr = n - 1;

            boolean is = true;

            int count = 0;
            List<Integer> ans = new ArrayList<>();
            while (l <= r) {
                if (is) {
                    if(a.charAt(l) == b.charAt(curr)) {
                        ans.add(1);
                    }
                    l += 1;
                    ans.add(n - count);

                    curr -= 1;
                    count += 1;
                    while(l <= r && a.charAt(l) != b.charAt(curr)) {
                        l += 1;
                        curr -= 1;
                        count += 1;
                    }
                } else {
                    if(a.charAt(r) != b.charAt(curr)) {
                        ans.add(1);
                    }
                    r -= 1;
                    ans.add(n - count);

                    curr -= 1;
                    count += 1;
                    while(l <= r && a.charAt(r) == b.charAt(curr)) {
                        r -= 1;
                        curr -= 1;
                        count += 1;
                    }
                }

                is = !is;
            }

            System.out.println(ans.size() + " " + ans.stream().map(String::valueOf).collect(Collectors.joining(" ")));
        }
    }
}

class Parser {
    private final Iterator<String> stringIterator;
    private final Deque<String> inputs;

    Parser() {
        this(System.in);
    }

    Parser(InputStream in) {
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        stringIterator = br.lines().iterator();
        inputs = new ArrayDeque<>();
    }

    void fill() {
        while (inputs.isEmpty()) {
            if (!stringIterator.hasNext()) throw new NoSuchElementException();
            inputs.addAll(Arrays.asList(stringIterator.next().split(" ")));
            while (!inputs.isEmpty() && inputs.getFirst().isEmpty()) {
                inputs.removeFirst();
            }
        }
    }

    Integer parseInt() {
        fill();
        if (!inputs.isEmpty()) {
            return Integer.parseInt(inputs.pollFirst());
        }
        throw new NoSuchElementException();
    }

    Long parseLong() {
        fill();
        if (!inputs.isEmpty()) {
            return Long.parseLong(inputs.pollFirst());
        }
        throw new NoSuchElementException();
    }

    Double parseDouble() {
        fill();
        if (!inputs.isEmpty()) {
            return Double.parseDouble(inputs.pollFirst());
        }
        throw new NoSuchElementException();
    }

    String parseString() {
        fill();
        return inputs.removeFirst();
    }
}