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 A {

	//public static Reader sc = new Reader();
	public static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	public static void main(String[] args) throws IOException {
		//BufferedReader br = new BufferedReader(new FileReader("input.in"));

		int t = Integer.parseInt(br.readLine());
		while (t-- > 0) {
			int n = Integer.parseInt(br.readLine());
			String s =br.readLine();
			String s2 = br.readLine();
			int[] c = new int[n];
			boolean flipped = false;
			int xor = 0;
			Deque<Integer> d = new ArrayDeque<Integer>();
			for (int i = 0; i < n; i++) {
				d.addLast(s.charAt(i)-'0');
				c[i] = s2.charAt(i)-'0';
			}
			//System.out.println(d);
			List<Integer> ops = new ArrayList<Integer>();
			for (int i = n-1; i >= 0; i--) {
				//System.out.println(d);
				if (!flipped) {
					int cc = d.peekLast()^xor;
					if (cc == c[i]) {
						//System.out.println("SKipped " + i);
						d.removeLast();
						continue;
					}
					else {
						if ((d.peekFirst()^xor) == c[i]) {
							ops.add(1);
						}
						ops.add(i+1);
						xor ^=1;
						flipped =!flipped;
						d.removeFirst();
					}
				}
				else {
					int cc = d.peekFirst()^xor;
					if (cc == c[i]) {
						//System.out.println("SKipped " + i);
						d.removeFirst();
						continue;
					}
					else {
						if ((d.peekLast()^xor)  == c[i]) {
							ops.add(1);
						}
						ops.add(i+1);
						xor ^=1;
						flipped =!flipped;
						d.removeLast();
					}
				}
				
			}
			out.print(ops.size() + " ");
			for (int x: ops) {
				out.print(x + " ");
			}
			out.println();
		}

		out.close();
	}

	static long ceil(long a, long b) {
		return (a + b - 1) / b;
	}

	static long powMod(long base, long exp, long mod) {
		if (base == 0 || base == 1)
			return base;
		if (exp == 0)
			return 1;
		if (exp == 1)
			return base % mod;
		long R = powMod(base, exp / 2, mod) % mod;
		R *= R;
		R %= mod;
		if ((exp & 1) == 1) {
			return base * R % mod;
		} else
			return R % mod;
	}

	static long pow(long base, long exp) {
		if (base == 0 || base == 1)
			return base;
		if (exp == 0)
			return 1;
		if (exp == 1)
			return base;
		long R = pow(base, exp / 2);
		if ((exp & 1) == 1) {
			return R * R * base;
		} else
			return R * R;
	}

	static class Reader {
		final private int BUFFER_SIZE = 1 << 16;
		private DataInputStream din;
		private byte[] buffer;
		private int bufferPointer, bytesRead;

		public Reader() {
			din = new DataInputStream(System.in);
			buffer = new byte[BUFFER_SIZE];
			bufferPointer = bytesRead = 0;
		}

		public Reader(String file_name) throws IOException {
			din = new DataInputStream(new FileInputStream(file_name));
			buffer = new byte[BUFFER_SIZE];
			bufferPointer = bytesRead = 0;
		}

		public String readLine() throws IOException {
			byte[] buf = new byte[64]; // line length 
			int cnt = 0, c;
			while ((c = read()) != -1) {
				if (c == '\n') {
					break;
				}
				buf[cnt++] = (byte) c;
			}
			return new String(buf, 0, Integer.max(cnt - 1, 0));
		}

		public int nextInt() throws IOException {
			int ret = 0;
			byte c = read();
			while (c <= ' ')
				c = read();
			boolean neg = (c == '-');
			if (neg)
				c = read();
			do {
				ret = ret * 10 + c - '0';
			} while ((c = read()) >= '0' && c <= '9');

			if (neg)
				return -ret;
			return ret;
		}

		public long nextLong() throws IOException {
			long ret = 0;
			byte c = read();
			while (c <= ' ')
				c = read();
			boolean neg = (c == '-');
			if (neg)
				c = read();
			do {
				ret = ret * 10 + c - '0';
			} while ((c = read()) >= '0' && c <= '9');
			if (neg)
				return -ret;
			return ret;
		}

		public double nextDouble() throws IOException {
			double ret = 0, div = 1;
			byte c = read();
			while (c <= ' ')
				c = read();
			boolean neg = (c == '-');
			if (neg)
				c = read();

			do {
				ret = ret * 10 + c - '0';
			} while ((c = read()) >= '0' && c <= '9');

			if (c == '.') {
				while ((c = read()) >= '0' && c <= '9') {
					ret += (c - '0') / (div *= 10);
				}
			}

			if (neg)
				return -ret;
			return ret;
		}

		private void fillBuffer() throws IOException {
			bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
			if (bytesRead == -1)
				buffer[0] = -1;
		}

		private byte read() throws IOException {
			if (bufferPointer == bytesRead)
				fillBuffer();
			return buffer[bufferPointer++];
		}

		public void close() throws IOException {
			if (din == null)
				return;
			din.close();
		}
	}

	public static PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));
}
