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>
using namespace std;
const int MAXN = 1e5 + 5;
int t, n;
int a[MAXN], b[MAXN];
int main() {
  scanf("%d", &t);
  while (t--) {
    scanf("%d", &n);
    for (int i = 0; i < n; i++) {
      scanf("%1d", &a[i]);
    }
    for (int i = 0; i < n; i++) {
      scanf("%1d", &b[i]);
    }
    vector<int> ans;
    vector<int> v;
    for (int i = 0; i < n; i++) {
      if (a[i] != b[i]) {
        v.push_back(i + 1);
        if (v.size() == 2) {
          if (a[v[0] - 1] == a[v[1] - 1]) {
            ans.push_back(v[1]);
            ans.push_back(2);
            ans.push_back(v[1]);
          } else {
            ans.push_back(v[0]);
            ans.push_back(v[1]);
            ans.push_back(v[0]);
            if (v[0] - 1 >= 1) ans.push_back(v[0] - 1);
          }
          v.clear();
        }
      } else {
        if (v.size() == 1) {
          ans.push_back(v[0]);
          ans.push_back(1);
          ans.push_back(v[0]);
        }
        v.clear();
      }
    }
    if (v.size()) {
      if (n == 1)
        ans.push_back(1);
      else {
        ans.push_back(v[0]);
        ans.push_back(1);
        ans.push_back(v[0]);
      }
    }
    printf("%d ", ans.size());
    for (int i = 0; i < ans.size(); i++) printf("%d ", ans[i]);
    puts("");
  }
  return 0;
}