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

public class Main {
	public static void main(String[] args) throws IOException{

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		// get number of employees in the company
		int e = Integer.parseInt(br.readLine());
		// array to hold costs for each employee 
		int[] q = new int[e + 1];
		int maxCost = 1000001;
		
		// fill array with maximum possible costs
		for (int i = 1; i <= e; i++)
			q[i] = maxCost;
		
		// skip a line of input since we do not actually need to know 
		// employee's specific qualifications
		br.readLine();
		// read in number of applications
		int apps = Integer.parseInt(br.readLine());
		
		// look at the data for each application 
		for (int i = 0; i < apps; i++) {
			
			// take input from each line for qualifications of employees 
			// and cost of making B supervisor of A
			StringTokenizer s = new StringTokenizer(br.readLine());
			int employeeA = Integer.parseInt(s.nextToken());
			int employeeB = Integer.parseInt(s.nextToken());
			int cost = Integer.parseInt(s.nextToken());

			// find the lowest cost to give employee B a supervisor
			// if the current cost is lower than the new cost, reassign
			if (q[employeeB] > cost)
				q[employeeB] = cost;
		}
		
		// variable to hold no. of employees without a supervisor 
		int empswosup = 0;
		// variable to hold minimum cost required
		int cost = 0;
		
		// check each index of q to see if a minimal cost has been assigned
		// to giving that employee a supervisor
		for (int i = 1; i <= e; i++){
			// if the index = maxCost, that means that employee does not have a 
			// supervisor...otherwise they must have a supervisor so add to sum
			// of costs
			if (q[i] != maxCost)
				cost += q[i];
			else
				empswosup++;
		}
		// if exactly one employee does not have a supervisor
		// then the hierarchy is possible, so print the cost
		// otherwise, the hierarchy is not possible
		if (empswosup > 1)
			System.out.println("-1");
		else 
			System.out.println(cost);
	}
}