Nick's company employed n people. Now Nick needs to build a tree hierarchy of «supervisor-surbodinate» relations in the company (this is to say that each employee, except one, has exactly one supervisor). There are m applications written in the following form: «employee ai is ready to become a supervisor of employee bi at extra cost ci». The qualification qj of each employee is known, and for each application the following is true: qai > qbi. 

Would you help Nick calculate the minimum cost of such a hierarchy, or find out that it is impossible to build it.

Input

The first input line contains integer n (1 ≤ n ≤ 1000) — amount of employees in the company. The following line contains n space-separated numbers qj (0 ≤ qj ≤ 106)— the employees' qualifications. The following line contains number m (0 ≤ m ≤ 10000) — amount of received applications. The following m lines contain the applications themselves, each of them in the form of three space-separated numbers: ai, bi and ci (1 ≤ ai, bi ≤ n, 0 ≤ ci ≤ 106). Different applications can be similar, i.e. they can come from one and the same employee who offered to become a supervisor of the same person but at a different cost. For each application qai > qbi.

Output

Output the only line — the minimum cost of building such a hierarchy, or -1 if it is impossible to build it.

Examples

Input

4
7 2 3 1
4
1 2 5
2 4 1
3 4 1
1 3 5


Output

11


Input

3
1 2 3
2
3 1 2
3 1 3


Output

-1

Note

In the first sample one of the possible ways for building a hierarchy is to take applications with indexes 1, 2 and 4, which give 11 as the minimum total cost. In the second sample it is impossible to build the required hierarchy, so the answer is -1.
#include <bits/stdc++.h>
using namespace std;
int n;
int q;
int m;
int a;
int b;
int c;
int employes[1001];
int min_costs[1001];
int maxCost = 10000000;
long long res = 0;
int bigSupervisor = 0;
int bestIndex = 0;
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    min_costs[i] = maxCost;
  }
  for (int i = 0; i < n; i++) {
    cin >> q;
    if (q > bigSupervisor) {
      bigSupervisor = q;
      bestIndex = (i + 1);
    }
  }
  cin >> m;
  for (int i = 0; i < m; i++) {
    cin >> a >> b >> c;
    if (c < min_costs[b]) {
      min_costs[b] = c;
    }
  }
  for (int i = 1; i <= n; i++) {
    if (i != bestIndex && min_costs[i] == maxCost) {
      cout << -1;
      return 0;
    } else if (i != bestIndex) {
      res += min_costs[i];
    }
  }
  cout << res;
  return 0;
}
