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.
//package cf_17b;

import java.io.*;
import java.util.*;

public class Main {
	
	public static class Employee{
		int empNum, cost;
		
		public Employee(int n, int c){
			this.empNum = n;
			this.cost = c;
		}
	}
	
	public static void main(String[] args) throws NumberFormatException, IOException{
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		//BufferedReader in = new BufferedReader(new FileReader("17bInput.txt"));
		
		int numEmployees = Integer.parseInt(in.readLine());

		String[] q = in.readLine().split(" ");
		
		Employee[] employees = new Employee[numEmployees + 1];
		Arrays.fill(employees, null);
		
		int numApps = Integer.parseInt(in.readLine());
		
		for(int i = 0; i < numApps; i++){
			String[] s = in.readLine().split(" ");
			int empA = Integer.parseInt(s[0]);
			int empB = Integer.parseInt(s[1]);
			int cost = Integer.parseInt(s[2]);
			
			if(employees[empB] == null){
				employees[empB] = new Employee(empA, cost);
			}
			else{
				if(cost < employees[empB].cost){
					employees[empB] = new Employee(empA, cost);
				}
			}
		}
		
		int total = 0;
		int noBoss = 0;
		for(int i = 1; i <= numEmployees; i++){
			if(employees[i] == null)
				noBoss++;
		}
		
		
		if(noBoss > 1){
			System.out.println(-1);
		}
		else{
			for(int i = 1; i <= numEmployees; i++){
				if(employees[i] != null)
					total += employees[i].cost;
			}
			System.out.println(total);
		}
		
		
	}
}
