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 = 1e6 + 10;
int n, t, A[maxn];
string tt[2];
deque<char> s[2];
bool d[2];
char get(int i, int j) {
  if (d[j]) {
    return '1' - s[j][int(s[j].size()) - 1 - i] + '0';
  } else {
    return s[j][i];
  }
}
int main() {
  cin >> t;
  while (t--) {
    d[0] = d[1] = 0;
    s[0].clear();
    s[1].clear();
    cin >> n >> tt[0] >> tt[1];
    for (int i = 0; i < n; i++) {
      s[0].push_back(tt[0][i]);
      s[1].push_back(tt[1][i]);
    }
    vector<int> v;
    for (int i = n - 1; i > 0; i--) {
      if (get(i, 0) != get(i, 1)) {
        if (get(0, 0) == get(i, 1)) {
          if (d[0] == 0) {
            s[0][0] = '1' - s[0][0] + '0';
          } else {
            s[0][s[0].size() - 1] = '1' - s[0][s[0].size() - 1] + '0';
          }
          v.push_back(1);
        }
        v.push_back(i + 1);
        d[0] ^= 1;
      }
      if (d[0] == 1) {
        s[0].pop_front();
      } else {
        s[0].pop_back();
      }
      s[1].pop_back();
    }
    if (get(0, 0) != get(0, 1)) {
      v.push_back(1);
    }
    cout << v.size() << ' ';
    for (int x : v) {
      cout << x << ' ';
    }
    cout << endl;
  }
}