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.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {

    static class Pair implements Comparable<Pair> {
        int first, second;

        public Pair(int first, int second) {
            this.first = first;
            this.second = second;
        }

        @Override
        public int compareTo(Pair o) {
            if (first != o.first)
                return -first + o.first;
            return -second + o.second;
        }

        @Override
        public String toString() {
            return "[first=" + first + ", second=" + second + "]";
        }
        
    }
    public static void main(String[] args) throws Exception {
        //System.setIn(new FileInputStream("1"));
        in = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);

        int n = nextInt();
        Pair[] q = new Pair[n];
        for (int i = 0; i < n; i++) {
            q[i] = new Pair(nextInt(), i);
        }
        Arrays.sort(q);
        int[][] gr = new int[n][n];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                gr[i][j] = Integer.MAX_VALUE;
            }
        }
        int m = nextInt();
        for (int i = 0; i < m; i++) {
            int a = nextInt() - 1;
            int b = nextInt() - 1;
            int c = nextInt();
            gr[a][b] = Math.min(gr[a][b], c);
        }
        int ans = 0;
        for (int ii = 1; ii < n; ii++) {
            int ans2 = Integer.MAX_VALUE;
            for (int jj = 0; jj < ii; jj++) {
                ans2 = Math.min(gr[q[jj].second][q[ii].second], ans2);
            }
            if (ans2 == Integer.MAX_VALUE) {
                ans = -1;
                break;
            }
            ans += ans2;
        }
        out.println(ans);
        
        in.close();
        out.close();
    }

    static BufferedReader in;
    static PrintWriter out;
    static StringTokenizer st;

    static String nextString() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }

    static int nextInt() throws NumberFormatException, IOException {
        return Integer.parseInt(nextString());
    }

    static double nextDouble() throws NumberFormatException, IOException {
        return Double.parseDouble(nextString());
    }
}
