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.ArrayList;


public class Main {
    static class Vertex
    {
        public int employeeNumber;
        public int qualifications;
        public int costToAdd;
        public Vertex supervisor;
        public boolean joined;
        public ArrayList<Edge> edges = new ArrayList<Edge>();
        
        
        public Vertex(int employeeNumber, int qualifications)
        {
            joined = false;
            costToAdd = Integer.MAX_VALUE;
            supervisor = this;
            this.employeeNumber = employeeNumber;
            this.qualifications = qualifications;
        }
    }
    
    static class Edge
    {
        public Vertex parent;
        public Vertex child;
        public int cost;
        
        public Edge(Vertex parent, Vertex child, int cost)
        {
            this.parent = parent;
            this.child = child;
            this.cost = cost;
        }
    }
    
    
    public static void main(String[] args) throws NumberFormatException, IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(in.readLine());
        String[] line = in.readLine().split(" ");
        int[] people = new int[n+1];
        ArrayList<Vertex> peopleVs = new ArrayList<Vertex>();
        peopleVs.add(new Vertex(Integer.MAX_VALUE,Integer.MAX_VALUE));
        
        for(int i=1; i<=n; i++)
        {
            people[i] = Integer.parseInt(line[i-1]);
            peopleVs.add(new Vertex(i, people[i]));
        }
        
        int m = Integer.parseInt(in.readLine());
        
        for(int i=0; i<m; i++)
        {
            line = in.readLine().split(" ");
            int a = Integer.parseInt(line[0]);
            int b = Integer.parseInt(line[1]);
            int c = Integer.parseInt(line[2]);
            
            peopleVs.get(a).edges.add(new Edge(peopleVs.get(a), peopleVs.get(b), c));
        }
        
        
        for(int i=1; i<=n; i++)
        {
            Vertex V = peopleVs.get(i);
            for(int j=0; j<V.edges.size(); j++)
            {
                if(V.edges.get(j).cost < V.edges.get(j).child.costToAdd)
                {
                    V.edges.get(j).child.costToAdd = V.edges.get(j).cost;
                    V.edges.get(j).child.supervisor = V;
                    V.edges.get(j).child.joined = true;
                }
            }
        }
        
        Vertex treeTop = null;
        boolean alreadyFound = false;
        
        for(int i=1; i<=n; i++)
        {
            Vertex V = peopleVs.get(i);
            if(V.joined == false)
            {
                if(alreadyFound)
                {
                    System.out.println(-1);
                    return;
                }
                else
                {
                    treeTop = V;
                    alreadyFound = true;
                    
                }
            }
            
        }
        treeTop.costToAdd=0;
        
        int totalCost=0;
        
        for(int i=1; i<=n; i++)
        {
            Vertex V = peopleVs.get(i);
            totalCost += V.costToAdd;
        }
        
        System.out.println(totalCost);

    }

}
