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;
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  long long t;
  cin >> t;
  while (t--) {
    long long n;
    cin >> n;
    string s1, s2;
    cin >> s1 >> s2;
    vector<long long> ans;
    long long cnt = 0;
    long long st = 0;
    long long en = n - 1;
    for (long long i = n - 1; i >= 0; i--) {
      char lst = s1[en];
      if (cnt % 2) lst = '0' + '1' - lst;
      if (lst == s2[i]) {
        if (cnt % 2)
          en++;
        else
          en--;
        continue;
      }
      char fst = s1[st];
      if (cnt % 2) fst = '0' + '1' - fst;
      if (fst == s2[i]) ans.push_back(1);
      ans.push_back(i + 1);
      cnt++;
      swap(st, en);
      if (cnt % 2)
        en++;
      else
        en--;
    }
    cout << ans.size() << ' ';
    for (__typeof(ans.size()) i = (0) - ((0) > (ans.size()));
         i != (ans.size()) - ((0) > (ans.size()));
         i += 1 - 2 * ((0) > (ans.size())))
      cout << ans[i] << ((i == (ans.size() - 1)) ? '\n' : ' ');
  }
  return 0;
}