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.*;
import java.util.*;

public class CommonSubsequence {

    static byte[][] dp;

    public static void main (String[] args) {
        InputReader in = new InputReader(System.in);
        OutputWriter out	=	new OutputWriter(System.out);
        int t = in.readInt();
        for (int z=1;z<=t;z++){
            int n = in.readInt();
            String a = in.next(), b = in.next();
            List<Integer> ans = new ArrayList<>();
            // List<Integer> ans1 = new ArrayList<>();
            int cnt = 0, first = 0, last = n-1;
            for (int i = n-1; i >= 0; i--) {
                char ch = a.charAt(last);
                if (cnt % 2 != 0) {
                    ch = (ch == '1') ? '0' : '1';
                }
                if (ch == b.charAt(i)) {
                    last = (cnt % 2 != 0) ? last+1 : last-1;
                    continue;
                }
                char ch0 = a.charAt(first);
                if (cnt % 2 != 0) {
                    ch0 = (ch0 == '1') ? '0' : '1';
                }
                if (ch0 == b.charAt(i)) {
                    ans.add(1);
                }
                ans.add(i+1);
                cnt++;
                int temp = last;
                last = (cnt % 2 != 0) ? first+1 : first-1;
                first = temp;
            }
            out.print(ans.size() + " ");
            for (int i = 0; i < ans.size(); i++) {
                out.print(ans.get(i) + " ");
            }
            out.print("\n");
        }
        out.close();
    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
        public InputReader(InputStream stream) {
            this.stream = stream;
        }
        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }
        public int readInt() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }
        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }
        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
        public String next() {
            return readString();
        }
        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

    static class OutputWriter {
        private final PrintWriter writer;
        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }
        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }
        public void print(Object...objects) {
            for (int i = 0; i < objects.length; i++) {
                if (i != 0)
                    writer.print(' ');
                writer.print(objects[i]);
            }
        }
        public void printLine(Object...objects) {
            print(objects);
            writer.println();
        }
        public void close() {
            writer.close();
        }
        public void flush() {
            writer.flush();
        }
    }
    static class IOUtils {
        public static int[] readIntArray(InputReader in, int size) {
            int[] array = new int[size];
            for (int i = 0; i < size; i++)
                array[i] = in.readInt();
            return array;
        }
    }

      /*//initialize
    InputReader in 		= new InputReader(System.in);
    OutputWriter out	=	new OutputWriter(System.out);

    //read int
    int i = in.readInt();
    //read string
    String s = in.readString();
    //read int array of size N
    int[] x = IOUtils.readIntArray(in,N);
//printline
   out.printLine("X");
//flush output
           out.flush();
//remember to close the
//outputstream, at the end
           out.close();*/
}
