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.*;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.*;
import static java.lang.Math.*;

public class Main {
    StreamTokenizer in;
    //BufferedReader in;
    PrintWriter out;
    public static void main(String[] args) throws IOException {
        new Main().run();
    }
    int ni() throws IOException {
        in.nextToken(); return (int)in.nval;
    }
    void run() throws IOException {
        //in = new StreamTokenizer(new BufferedReader(new FileReader("input.txt")));
        in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        out = new PrintWriter(new OutputStreamWriter(System.out));
        //out = new PrintWriter(new FileWriter("output.txt"));
        int n = ni();
        C[] q = new C[n];
        for(int i = 0; i < n; i++) q[i] = new C(ni(), i);
        Arrays.sort(q);
        int[][] c = new int[n][n];
        for(int i = 0; i < n; i++)
            Arrays.fill(c[i], Integer.MAX_VALUE);
        int m = ni();
        for(int i = 0; i < m; i++) {
            int a = ni() - 1, b = ni() - 1, t = ni();
            c[b][a] = min(c[b][a], t);
        }
        int ret = 0;
        for(int i = 0; i < n; i++) {
                int k = Integer.MAX_VALUE;
                for(int j = 0; j < n; j++) {
                    if(k > c[q[i].id][j]) {
                        k = c[q[i].id][j];
                    }
                }
                if(k == Integer.MAX_VALUE && i != n - 1) {
                    out.print(-1); out.flush(); return;
                }
                else if(k != Integer.MAX_VALUE)
                    ret += k;
            }
        out.print(ret);
        out.flush();
    }
    class C implements Comparable<C> {
        int q; int id;
        public int compareTo(C c) {
            return q < c.q ? -1 : 1;
        }
        public C(int q_, int id_) {
            q = q_; id = id_;
        }
    }
}