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 long long MOD = 1e9 + 7;
const long long INF = 1e18;
const double PI = acos(-1.0);
const int maxn = (int)5e5 + 13;
void solve() {
  int n;
  string a, b;
  cin >> n >> a >> b;
  vector<int> va;
  for (int i = 0; i < (int)n - 1; ++i) {
    if (a[i] != a[i + 1]) va.push_back(i + 1);
  }
  if ((int)(va.size()) % 2 != a[0] - '0') va.push_back(n);
  vector<int> vb;
  for (int i = 0; i < (int)n - 1; ++i) {
    if (b[i] != b[i + 1]) vb.push_back(i + 1);
  }
  if ((int)(vb.size()) % 2 != b[0] - '0') vb.push_back(n);
  cout << (int)(va.size()) + (int)(vb.size()) << "\n";
  for (int i = 0; i < (int)(int)(va.size()); ++i) cout << va[i] << " ";
  for (int i = (int)(vb.size()) - 1; i >= 0; --i) cout << vb[i] << " ";
  cout << "\n";
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t;
  cin >> t;
  while (t--) solve();
  return 0;
}