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;

public class CF17B {

    public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(in.readLine());
        String[] input = in.readLine().split(" ");
        int[] q = new int[n+1];
        int[] cost = new int[n+1];
        for(int i = 1; i <= n; ++i)
        {
            q[i] = Integer.parseInt(input[i-1]);
            cost[i] = Integer.MAX_VALUE;
        }
        int m = Integer.parseInt(in.readLine());
        while(m-- > 0)
        {
            input = in.readLine().split(" ");
            int a = Integer.parseInt(input[0]);
            int b = Integer.parseInt(input[1]);
            int c = Integer.parseInt(input[2]);
            if(cost[b] > c)
            {
                cost[b] = c;
            }
        }
        int sum = 0;
        int emplyWithNoSuper = 0;
        for(int i = 1; i <= n; ++i)
        {
            
            if(cost[i] == Integer.MAX_VALUE)
            {
                ++emplyWithNoSuper;
            }
            else
            {
                sum += cost[i];
            }
            if(emplyWithNoSuper > 1)
            {
                System.out.println(-1);
                return;
            }
        }
        System.out.println(sum);

    }

}