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>
#pragma GCC optimize("Ofast", "inline")
using namespace std;
template <class T>
inline void read(T &x) {
  int ch = 0, f = 0;
  x = 0;
  for (; !isdigit(ch); ch = getchar())
    if (ch == '-') f = 1;
  for (; isdigit(ch); ch = getchar()) x = x * 10 + ch - 48;
  if (f) x = -x;
}
const int N = 100005;
vector<int> ans;
char a[N], b[N];
int c[N], d[N];
int n, now;
int main() {
  int T;
  read(T);
  while (T--) {
    read(n);
    scanf("%s", a + 1);
    scanf("%s", b + 1);
    ans.clear();
    int m = 0;
    for (int i = n; i >= 1; i -= 2) {
      c[++m] = ((a[i] - '0') ^ 1) + '0';
      d[i] = m;
    }
    for (int i = (n & 1) + 1; i <= n; i += 2) {
      c[++m] = a[i];
      d[i] = m;
    }
    for (int i = 1; i <= n; i++) {
      ans.push_back(i);
      if (c[d[i]] != b[d[i]]) ans.push_back(1);
    }
    printf("%d\n", (int)ans.size());
    for (auto x : ans) printf("%d ", x);
    puts("");
  }
  return 0;
}