You are given two strings s and t, each of length n and consisting of lowercase Latin alphabets. You want to make s equal to t. 

You can perform the following operation on s any number of times to achieve it — 

  * Choose any substring of s and rotate it clockwise once, that is, if the selected substring is s[l,l+1...r], then it becomes s[r,l,l + 1 ... r - 1]. All the remaining characters of s stay in their position. 

For example, on rotating the substring [2,4] , string "abcde" becomes "adbce". 




A string a is a substring of a string b if a can be obtained from b by deletion of several (possibly, zero or all) characters from the beginning and several (possibly, zero or all) characters from the end.

Find the minimum number of operations required to convert s to t, or determine that it's impossible.

Input

The first line of the input contains a single integer t (1≤ t ≤ 2000) — the number of test cases. The description of the test cases follows.

The first line of each test case contains a single integer n (1≤ n ≤ 2000) — the length of the strings. 

The second and the third lines contain strings s and t respectively.

The sum of n over all the test cases does not exceed 2000.

Output

For each test case, output the minimum number of operations to convert s to t. If it is not possible to convert s to t, output -1 instead.

Example

Input


6
1
a
a
2
ab
ba
3
abc
cab
3
abc
cba
4
abab
baba
4
abcc
aabc


Output


0
1
1
2
1
-1

Note

For the 1-st test case, since s and t are equal, you don't need to apply any operation.

For the 2-nd test case, you only need to apply one operation on the entire string ab to convert it to ba.

For the 3-rd test case, you only need to apply one operation on the entire string abc to convert it to cab.

For the 4-th test case, you need to apply the operation twice: first on the entire string abc to convert it to cab and then on the substring of length 2 beginning at the second character to convert it to cba.

For the 5-th test case, you only need to apply one operation on the entire string abab to convert it to baba.

For the 6-th test case, it is not possible to convert string s to t.
#include <bits/stdc++.h>
using namespace std;
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  os << '{';
  string sep;
  for (const auto &x : v) os << sep << x, sep = ", ";
  return os << '}';
}
template <typename T, size_t size>
ostream &operator<<(ostream &os, const array<T, size> &arr) {
  os << '{';
  string sep;
  for (const auto &x : arr) os << sep << x, sep = ", ";
  return os << '}';
}
template <typename A, typename B>
ostream &operator<<(ostream &os, const pair<A, B> &p) {
  return os << '(' << p.first << ", " << p.second << ')';
}
void dbg_out() { cerr << endl; }
template <typename Head, typename... Tail>
void dbg_out(Head H, Tail... T) {
  cerr << ' ' << H;
  dbg_out(T...);
}
const int INF = 1e9 + 5;
const int ALPHABET = 26;
const char MIN_CHAR = 'a';
string sorted(string str) {
  sort(str.begin(), str.end());
  return str;
}
void run_case() {
  int N;
  string S, T;
  cin >> N >> S >> T;
  if (sorted(S) != sorted(T)) {
    cout << -1 << '\n';
    return;
  }
  vector<int> dp(N + 1, 0);
  vector<int> S_freq(ALPHABET, 0);
  for (int i = 0; i < N; i++) {
    vector<int> next_dp(N + 1, INF);
    int minimum = INF;
    int goal_ch = S[i] - MIN_CHAR;
    S_freq[goal_ch]++;
    vector<int> T_freq(ALPHABET, 0);
    for (int j = 0; j < N; j++) {
      if (S[i] == T[j]) minimum = min(minimum, dp[j]);
      next_dp[j + 1] = minimum;
      T_freq[T[j] - MIN_CHAR]++;
      if (T_freq[goal_ch] >= S_freq[goal_ch])
        next_dp[j + 1] = min(next_dp[j + 1], dp[j + 1] + 1);
    }
    swap(dp, next_dp);
  }
  cout << dp[N] << '\n';
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int tests;
  cin >> tests;
  while (tests-- > 0) run_case();
}
