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.IOException;
import java.io.InputStreamReader;

public class A {

	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader file = new BufferedReader(new InputStreamReader(System.in));
		int inputs = Integer.parseInt(file.readLine());
		while(inputs-->0) {
			int n = Integer.parseInt(file.readLine());
			char[] a = file.readLine().toCharArray();
			char[] b = file.readLine().toCharArray();
			int moves = 0;
			int left = 0;
			int right = n-1;
			StringBuilder ans = new StringBuilder();
			for(int i = 0; i < n; i++) {
				int c = -1;
				if(i%2==0) { 
					c = a[left++];
				}
				else {
					c = a[right--];
				}
				c = (c+i-'0')%2;
//				System.out.println(i + " " + c);
//				System.out.println(c + " " + (b[n-i-1]-'0'));
				if(c == b[n-i-1]-'0') {
					moves++;
					ans.append("1 ");
				}
				moves++;
				ans.append((n-i) + " ");
			}
			System.out.println(moves + " " + ans);
		}

	}

}
