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.util.*;
public class Answer17B{
    public static void main(String[] args){
	try{
	    BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));
	    int n=to_i(reader.readLine());
	    String[] tmp=reader.readLine().split(" ");
	    int[] q=new int[n];
	    for(int i=0;i<n;i++){
		q[i]=to_i(tmp[i]);
	    }
	    int m=to_i(reader.readLine());
	    int[] memo=new int[n];
	    Arrays.fill(memo,Integer.MAX_VALUE);
	    for(int j=0;j<m;j++){
		tmp=reader.readLine().split(" ");
		int a=to_i(tmp[0])-1;
		int b=to_i(tmp[1])-1;
		int c=to_i(tmp[2]);
		if(memo[b]>c){
		    memo[b]=c;
		}
	    }
	    int sum=0;
	    int cnt=0;
	    for(int i=0;i<n;i++){
		if(memo[i]<Integer.MAX_VALUE){
		    sum+=memo[i];
		}else{
		    cnt++;
		}
	    }
	    if(cnt==1)System.out.println(sum);
	    else System.out.println(-1);
	}catch(IOException e){
	    e.printStackTrace();
	}
    }
    public static int to_i(String s){
	return Integer.parseInt(s);
    }
}