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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

/**
 * Created by joshua on 3/26/15.
 */
public class Hierarchy {

	public static void main(String[] args) throws IOException
	{
		BufferedReader console = new BufferedReader(new InputStreamReader(System.in));

		int numEmps = Integer.parseInt(console.readLine());
		int[] costs = new int[numEmps+1];
		Arrays.fill(costs, Integer.MAX_VALUE);

		// actually don't use qualifications...
		String qualifications = console.readLine();
		int numApps = Integer.parseInt(console.readLine());
		for(int n=0; n<numApps; n++) {
			String[] temp = console.readLine().split(" ");
			// don't need the supervisor
			int employee = Integer.parseInt(temp[1]);
			int cost = Integer.parseInt(temp[2]);

			if(costs[employee] > cost)
				costs[employee] = cost;
		}

		int rootCount = 0;
		int totalCost = 0;
		for(int i : costs) {
			if(i == Integer.MAX_VALUE)
				rootCount++;
			else
				totalCost += i;
		}

		// 2 because the first value isn't used
		if(rootCount > 2)
			System.out.println("-1");
		else
			System.out.println(totalCost);
	}
}
