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;
char getValue(string &A, int contador, int indx, int suma) {
  int v = 0;
  char ans;
  if (contador % 2) {
    ans = A[-indx + suma];
    if (ans == '0')
      ans = '1';
    else
      ans = '0';
    v = -indx + suma;
  } else {
    ans = A[indx + suma];
    v = indx + suma;
  }
  return ans;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    string A, B;
    cin >> A >> B;
    int suma = 0;
    int contador = 0;
    vector<int> changes;
    int indx = n - 1;
    int realContador = 0;
    while (indx >= 0) {
      char Aindx = getValue(A, contador, indx, suma);
      if (Aindx != B[indx]) {
        char A0 = getValue(A, contador, 0, suma);
        if (A0 != B[indx]) {
          contador++;
          realContador++;
          changes.push_back(indx + 1);
          if (contador % 2) {
            suma += (indx);
          } else
            suma -= (indx);
          indx--;
        } else {
          realContador++;
          changes.push_back(1);
          contador++;
          realContador++;
          if (contador % 2) {
            suma += (indx);
          } else {
            suma -= (indx);
          }
          changes.push_back(indx + 1);
          indx--;
        }
      } else
        indx--;
    }
    cout << realContador;
    for (int i = 0; i < changes.size(); i++) {
      cout << " " << changes[i];
    }
    cout << "\n";
  }
  return 0;
}