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.
/**
 * Codeforces Beta Round 17
 * 
 * @author ProjectYoung
 * @keyword greedy
 */

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class CF17B {
  private void solve(InputReader in, PrintWriter out) {
    int n = in.nextInt();
    for (int i = 0; i < n; i++) {
      in.nextInt();
    }
    int m = in.nextInt();
    int[] minCost = new int[n];
    for (int i = 0; i < n; i++) {
      minCost[i] = Integer.MAX_VALUE;
    }
    // For each employee, find the minimal cost to find a supervisor for him.
    for (int i = 0; i < m; i++) {
      in.nextInt();
      int b = in.nextInt() - 1;
      int c = in.nextInt();
      minCost[b] = Math.min(minCost[b], c);
    }
    int root = 0;
    for (int i = 0; i < n; i++) {
      if (minCost[i] == Integer.MAX_VALUE) {
        root++;
      }
    }
    if (root > 1) {
      out.println(-1);
      return;
    }
    int sum = 0;
    for (int i = 0; i < n; i++) {
      sum += minCost[i] == Integer.MAX_VALUE ? 0 : minCost[i];
    }
    out.println(sum);
  }

  public static void main(String[] args) {
    InputReader in = new InputReader(System.in);
    PrintWriter out = new PrintWriter(System.out);
    new CF17B().solve(in, out);
    out.close();
  }

  static class InputReader {
    public BufferedReader reader;
    public StringTokenizer tokenizer;

    public InputReader(InputStream stream) {
      reader = new BufferedReader(new InputStreamReader(stream));
      tokenizer = null;
    }

    public String next() {
      while (tokenizer == null || !tokenizer.hasMoreTokens()) {
        try {
          tokenizer = new StringTokenizer(reader.readLine());
        } catch (IOException e) {
          throw new RuntimeException(e);
        }
      }
      return tokenizer.nextToken();
    }

    public int nextInt() {
      return Integer.parseInt(next());
    }
  }
}
