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 
{
    public static class Employee
    {
        int id;
        int cost;
        public Employee(int id, int cost)
        {
            this.id=id;
            this.cost=cost;
            
        }
        
    }
    public static void main(String args[]) throws IOException
    {
        
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        //BufferedReader reader = new BufferedReader(new FileReader("employees"));
    
        int empCount=Integer.parseInt(reader.readLine());
        reader.readLine();
        
        int cases=Integer.parseInt(reader.readLine());
        
        HashMap<Integer, Employee> hash=new HashMap<>();
        
        for(int i=1; i<=empCount; i++)
        {
            hash.put(i,null);
        }
        for(int i=0; i<cases; i++)
        {
            String [] input=reader.readLine().split(" ");
            int a=Integer.parseInt(input[0]);
            int b=Integer.parseInt(input[1]);
            int c=Integer.parseInt(input[2]);
            
            if(hash.get(b)==null)
            {
                hash.put(b, new Employee(a,c));
            }
            else
            {
                int cost1=hash.get(b).cost;
                if(c<cost1)
                {
                    hash.put(b, new Employee(a,c));
                }
                
            }
            
            
        }
        
        int nullCount=0;
        int total=0;
        
        for(int i=1; i<=empCount; i++)
        {
            if(hash.get(i)==null)
            {
                nullCount++;
            }
            else
            {
                total+=hash.get(i).cost;
            }
            
            
        }
        
        if(nullCount>1)
        {
            System.out.println("-1");
        }
        else
        {
            System.out.println(total);
        }
        
        
        
    }
}
