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.util.HashMap;



public class Main {
	
	public static void main(String[] args)throws IOException{
			BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		
			int n = Integer.parseInt(in.readLine());
			int matrix [] = new int [n];
			for(int i = 0; i < n; ++i){
				matrix [i] = -1;
			}
			int [] q = new int[n];
			String [] line = in.readLine().split(" ");
			for(int i = 0; i < n; ++i){
				q[i] = Integer.parseInt(line[i]);
			}
			int m = Integer.parseInt(in.readLine());
			int cost = 0;
			
			for(int i = 0; i < m; ++i){
				line = in.readLine().split(" ");
				int a = Integer.parseInt(line[0])-1;
				int b = Integer.parseInt(line[1])-1;
				int c = Integer.parseInt(line[2]);
				if(q[a]>q[b]){
					if(matrix[b]==-1 || matrix[b] > c){
						cost+=c;
						if(matrix[b]>0)cost-=matrix[b];
						matrix[b] = c;
					}
				}
			}
			int one = 0;
			for(int i = 0; i < n; ++i){
				if(matrix[i] == -1){
					++one;
					if(one>1){
						System.out.println(-1);
						return;
					}
				}
			}
			System.out.println(cost);
			in.close();
		}
};