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;
void rev(string &s, int n, int m) {
  while (n < m) {
    char c = s[n];
    s[n] = s[m];
    s[m] = c;
    n++;
    m--;
  }
}
void flip(string &s, int n, int m) {
  while (n != m) {
    if (s[n] == '0')
      s[n] = '1';
    else
      s[n] = '0';
    n++;
  }
}
void swap(char &a, char &b) {
  char temp = a;
  a = b;
  b = temp;
}
void shift(string &s, int m) {
  int i, j;
  i = 0;
  j = m;
  while (i < j) {
    swap(s[i], s[j]);
    j--;
    i++;
  }
  for (int l = 0; l < m; l++) {
    if (s[l] == '1')
      s[l] = '0';
    else
      s[l] = '1';
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int t;
  cin >> t;
  while (t--) {
    int n, m;
    string s1, s2;
    cin >> n >> s1 >> s2;
    int count = 0;
    m = 0;
    vector<int> v;
    vector<int> v1;
    for (int i = n - 1; i > 0; i--) {
      if (s1[i] != s2[i]) {
        if (s1[0] != s1[i]) v.push_back(0), s1[0] = s1[i];
        v.push_back(i);
        shift(s1, i);
      }
    }
    if (s1[0] != s2[0]) v.push_back(0);
    cout << v.size() << " ";
    for (int it : v) {
      cout << it + 1 << " ";
    }
    cout << "\n";
  }
  return 0;
}