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.
import java.util.Scanner;
import java.util.List;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Comparator;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Collections;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		Scanner in = new Scanner(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		TaskB solver = new TaskB();
		solver.solve(1, in, out);
		out.close();
	}
}

class TaskB {
    public void solve(int testNumber, Scanner in, PrintWriter out) {
        final int n = Integer.parseInt(in.nextLine());
        final int[] parents = new int[n + 1];

        for (int i = 0; i <= n; i++) {
            parents[i] = i;
        }

        in.nextLine();

        final int m = Integer.parseInt(in.nextLine());
        final ArrayList<Offer> offers = new ArrayList<Offer>(m);

        for (int i = 0; i < m; i++) {
            offers.add(new Offer(in.nextInt(), in.nextInt(), in.nextInt()));
            in.nextLine();
        }

        Collections.sort(offers, new Comparator<Offer>() {
            @Override
            public int compare(Offer o1, Offer o2) {
                return o2.amount - o1.amount;
            }
        });

        long edgesSum = 0, edgesNumber = 0;

        while (true) {
            boolean nonChanged = true;

            for (int i = offers.size() - 1; -1 < i; i--) {
                final Offer offer = offers.get(i);

                int parentA = parent(parents, offer.a);
                int parentB = parent(parents, offer.b);

                if (parentA != parentB && parentB == offer.b) {
                    edgesNumber++;
                    edgesSum += offer.amount;
                    nonChanged = false;

                    parents[offer.b] = parentA;
                }

                offers.remove(i);
            }

            if (nonChanged) {
                break;
            }
        }

        if (n - 1 == edgesNumber) {
            out.println(edgesSum);
        } else {
            out.println(-1);
        }
    }

    private static int parent(int[] parents, int index) {
        if (index == parents[index]) {
            return index;
        }

        return parent(parents, parents[index]);
    }

    private static class Offer {
        private int a;
        private int b;
        private int amount;

        private Offer(int a, int b, int amount) {
            this.a = a;
            this.b = b;
            this.amount = amount;
        }

        public String toString() {
            return "Offer{" +
                    "a=" + a +
                    ", b=" + b +
                    ", amount=" + amount +
                    '}';
        }
    }
}

