Problem: 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.

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
int main(int argc, char *argv[]) {
  int tc;
  scanf("%d", &tc);
  while (tc--) {
    char a[100005], b[100005];
    int n, i, j = 0, ans[200005], det = 0, p, q;
    scanf("%d%s%s", &n, a, b);
    p = 1, q = n - 1;
    for (i = n - 1; i >= 1; i--) {
      det++;
      if (a[0] == b[i]) ans[j++] = 1;
      ans[j++] = i + 1;
      if (det % 2 == 0) {
        a[0] = a[p];
        p++;
      } else if (det % 2) {
        if (a[q] == '0')
          a[0] = '1';
        else
          a[0] = '0';
        q--;
      }
    }
    if (a[0] != b[0]) ans[j++] = 1;
    printf("%d ", j);
    for (i = 0; i < j; i++) printf("%d ", ans[i]);
    printf("\n");
  }
}