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 Hierarchy {
    public static void main(String[] args) throws IOException{
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int N =Integer.parseInt(in.readLine());
        String[] line=in.readLine().split(" ");
        int[] q=new int[N];
        int[] cost=new int[N];
        for (int i= 0;i<N;++i){
            q[i]=Integer.parseInt(line[i]);
            cost[i]=-1;
        }
        int T =Integer.parseInt(in.readLine());
        for (int i= 0;i<T;++i){
            line=in.readLine().split(" ");
            int a=Integer.parseInt(line[0])-1;
            int b=Integer.parseInt(line[1])-1;
            int c=Integer.parseInt(line[2]);
            if(q[a]>q[b]&&(cost[b]==-1||c<cost[b]))cost[b]=c;
        }
        boolean sup=false;
        long Kost=0;
        for (int i= 0;i<N;++i){
            if(cost[i]==-1){
                if(sup){
                    System.out.print("-1"); 
                    return;
                }
                sup=true;
            }else{
                Kost+=cost[i];
            }
        }
        System.out.print(""+Kost);      
    }
}
