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 B {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		String s = new String(in.readLine());
        int n = Integer.parseInt(s);
//      System.out.println("n="+n);
        int[] q=new int[n];
		s = new String(in.readLine());
        String[] t=s.split(" ");
        for (int i=0;i<n;i++) {
            q[i] = Integer.parseInt(t[i]);
//          System.out.println("q["+i+"]="+q[i]);
        }
		s = new String(in.readLine());
        int m = Integer.parseInt(s);
//      System.out.println("m="+m);
        int a,b,c;
        int[] cost=new int[n+1];
        for (int i=1;i<=n;i++) {
        	cost[i]=9999999;
        }
        int emp=0;
        for (int i=0;i<m;i++) {
    		s = new String(in.readLine());
            t=s.split(" ");
            a = Integer.parseInt(t[0]);
            b = Integer.parseInt(t[1]);
            c = Integer.parseInt(t[2]);
//          System.out.println("a,b,c["+i+"]="+a+","+b+","+c);
            if (cost[b]==9999999) {
            	emp++;
            }
            if (c<cost[b]) {
            	cost[b]=c;
            }
        }
        if (emp<n-1) {
        	System.out.println(-1);
        } else {
        	int sum=0;
        	for (int i=1;i<=n;i++) {
        		if (cost[i]<9999999) {
        			sum=sum+cost[i];
        		}
        	}
        	System.out.println(sum);
        }
	}
}
