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.*;
import java.util.*;

public class Hierarchy 
{
	static class Edge implements Comparable<Edge>
	{
		int supervisor, subordinate, cost;
		
		Edge(int sup, int sub, int c)
		{
			supervisor = sup;
			subordinate = sub;
			cost = c;
			
		}

		@Override
		public int compareTo(Edge other) 
		{
			return this.cost - other.cost;
		}
		
		
	}
	public static void main(String[] args) throws NumberFormatException, IOException
	{
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		int employeeCount = Integer.parseInt(input.readLine());
		String[] empQual = input.readLine().split(" ");
		int[] qualifications = new int[employeeCount];
		int applicationCount = Integer.parseInt(input.readLine());
		
		Edge[] applications = new Edge[applicationCount];
		boolean[] hasPossibleSupervisor = new boolean[employeeCount];
		boolean[] assignedSupervisor = new boolean[employeeCount];
		boolean[] inGraph = new boolean[employeeCount];
		boolean possible = true;
						
		/*for (int e = 0; e < employeeCount; ++e)
		{
			qualifications[e] = Integer.parseInt(empQual[e]);
		}*/
		
		for (int app = 0; app < applicationCount; ++app)
		{
			String[] applicationInfo = input.readLine().split(" ");
			int supervisor = Integer.parseInt(applicationInfo[0]) - 1;
			int subordinate = Integer.parseInt(applicationInfo[1]) - 1;
			int cost = Integer.parseInt(applicationInfo[2]);
			
			if (!hasPossibleSupervisor[subordinate])
				hasPossibleSupervisor[subordinate] = true;
			
			applications[app] = new Edge(supervisor, subordinate, cost);
		}
		
		int noSupervisorCount = 0;
		
		for (boolean possSup : hasPossibleSupervisor)
		{
			if (!possSup)
			{
				noSupervisorCount++;
			}
			
			if (noSupervisorCount > 1)
			{
				possible = false;
				break;
			}
		}
		
		Arrays.sort(applications);
		int totalCost = 0;
		
		if (possible)
		{
			for (Edge application : applications)
			{
				if (!inGraph[application.supervisor] && !inGraph[application.subordinate])
				{
					inGraph[application.supervisor] = true;
					inGraph[application.subordinate] = true;
					assignedSupervisor[application.subordinate] = true;
					totalCost += application.cost;
				}
				
				else if (!inGraph[application.supervisor] && !assignedSupervisor[application.subordinate])
				{
					inGraph[application.supervisor] = true;
					assignedSupervisor[application.subordinate] = true;
					totalCost += application.cost;
				}
								
				else if (!assignedSupervisor[application.subordinate] || !inGraph[application.subordinate])
				{
					inGraph[application.subordinate] = true;
					assignedSupervisor[application.subordinate] = true;
					totalCost += application.cost;
				}
			}
		}
		
		if (!possible)
		{
			System.out.println("-1");
		}
		
		else
			System.out.println(totalCost);
		
		
	}
	

}
