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;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;

public class Solution {
    private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[] args) throws IOException {

        int n= nextInt();
        int arr[]= readIntArray();
        int q= nextInt();
        int sum=0;
        int parents[]= new int[n+1];
        HashMap<Integer,int[]> map= new HashMap<>();
        while(q-->0){
            int inp[]= readIntArray();
            int child= inp[1];
            int parent= inp[0];
            int cost= inp[2];
            if(map.containsKey(child)){
                if(map.get(child)[1]>cost){
                    sum-= map.get(child)[1];
                    sum+=cost;
                    parents[child]=parent;
                    map.put(child,new int[]{parent,cost});
                }
            }
            else{
                map.put(child,new int[]{parent,cost});
                parents[child]=parent;
                sum+=cost;
            }
        }
        int withoutParent=0;
        for(int i=1;i<=n;i++){
            if(parents[i]==0)
                withoutParent++;
        }
        
        if(withoutParent==1)
            println(sum);
        else
            println(-1);

    }



// *********************************************************************************************** //

    public static String readLine() throws IOException{
        return br.readLine();
    }
    public static String[] readStringArray()throws  IOException{
        return br.readLine().split(" ");
    }
    public static int[] readIntArray()throws IOException{
        return Arrays.stream(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    public static long[] readLongArray() throws IOException{
        return Arrays.stream(br.readLine().split(" ")).mapToLong(Long::parseLong).toArray();
    }
    public static long nextLong()throws IOException{
        return Long.parseLong(br.readLine().trim());
    }
    public static int nextInt()throws IOException{
        return Integer.parseInt(br.readLine().trim());
    }

    public static void println(String out){
        System.out.println(out);
    }

    public static void println(int out){
        System.out.println(out);
    }

    public static void println(double out){
        System.out.print(out);
    }

    public static void print(String out){
        System.out.print(out);
    }

    public static void print(int out){
        System.out.print(out);
    }

    public static void print(double out){
        System.out.print(out);
    }
}
