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.InputStreamReader;
import java.io.PrintWriter;
import java.io.StreamTokenizer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;

public class Main {
    private static StreamTokenizer in;
    private static PrintWriter out;
    private static BufferedReader inB;
    
    private static int nextInt() throws Exception{
        in.nextToken();
        return (int)in.nval;
    }
    
    private static String nextString() throws Exception{
        in.nextToken();
        return in.sval;
    }
    
    static{
        inB = new BufferedReader(new InputStreamReader(System.in));
        in = new StreamTokenizer(inB);
        out = new PrintWriter(System.out);
    }
    
    public static void main(String[] args)throws Exception {
        int n = nextInt();
        
        int[] q = new int[n];
        int boss = Integer.MIN_VALUE, bossi = -1, col = 0;
        for(int i = 0; i<n; i++) {
            q[i] = nextInt();
            if(q[i] > boss) {
                boss = q[i];
                bossi = i;
                col = 1;
                continue;
            }
            if(q[i] == boss)col++;
        }
        
        if(bossi == -1 || col != 1) {
            System.out.println(-1);
            return;
        }
        
        int[] p = new int[n];
        int[] cost = new int[n];
        
        Arrays.fill(p, -1);
        
        int m = nextInt();
        
        for(int i = 0; i<m; i++) {
            int a = nextInt()-1, b = nextInt()-1, c = nextInt();
            
            if(p[b] == -1 || c < cost[b]) {
                p[b] = a;
                cost[b] = c;
            }
            
        }
        
        int sum = 0;
        for(int i = 0; i<n; i++) {
            if(p[i] == -1 && i != bossi) {
                System.out.println(-1);
                return;
            }
            sum += cost[i];
        }
        System.out.println(sum);
    }
}

