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;
template <typename T>
inline void read(T& t) {
  t = 0;
  int f = 1;
  char ch = getchar();
  while (!isdigit(ch)) {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (isdigit(ch)) {
    t = t * 10 + ch - '0';
    ch = getchar();
  }
  t *= f;
}
const int dx[] = {0, 1, 0, -1};
const int dy[] = {1, 0, -1, 0};
const long long Inf = 0x7f7f7f7f7f7f7f7f;
const int inf = 0x7f7f7f7f;
const double eps = 1e-5;
const double Pi = acos(-1);
string s1, s2;
vector<int> res;
int main(void) {
  int T;
  read(T);
  while (T--) {
    res.clear();
    int n;
    read(n);
    cin >> s1 >> s2;
    int cnt = 0;
    for (int i = 0; i <= n - 1; i++) {
      int pos = n - 1 - i / 2;
      if (i % 2 == 0) pos = n - 1 - pos;
      char ch = s1[pos];
      if (cnt & 1) ch = (ch == '0' ? '1' : '0');
      if (ch == s2[n - i - 1]) res.push_back(1);
      res.push_back(n - i);
      cnt++;
    }
    printf("%d ", res.size());
    for (int i = 0; i < res.size(); i++) printf("%d ", res[i]);
    printf("\n");
  }
  return 0;
}