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;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		String line = br.readLine();
		int numEmployees = Integer.parseInt(line);
		boolean[] isBeaten = new boolean[numEmployees + 1];
		int[] currCost = new int[numEmployees + 1];
		int beatenCount = 0;
		int totalCost = 0;
		
		for(int i = 0; i <= numEmployees; i++)
			currCost[i] = Integer.MAX_VALUE;
		
		line = br.readLine();
		line = br.readLine();
		int numApps = Integer.parseInt(line);
				
		for(int i = 0; i < numApps;  i++)
		{
			String[] lineString = br.readLine().split(" ");	
			int emp2 = Integer.parseInt(lineString[1]);
			int cost = Integer.parseInt(lineString[2]);
			
			if(isBeaten[emp2] == false)
				beatenCount++;
				
			isBeaten[emp2] = true;
				
			if(cost < currCost[emp2])
			{
				currCost[emp2] = cost;
			}
		}
		
		for(int i = 0; i <= numEmployees; i++)
		{
			if(currCost[i] != Integer.MAX_VALUE)
			totalCost += currCost[i];
		}
		
		if(numEmployees - beatenCount != 1)
			System.out.println("-1");
		
		else System.out.println(totalCost);
	}
}
