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.io.StreamTokenizer;
import java.util.Arrays;

public class B17 {

	static StreamTokenizer in;
	static PrintWriter out;
	
	static int nextInt() throws IOException {
		in.nextToken();
		return (int)in.nval;
	}
	
	static String nextString() throws IOException {
		in.nextToken();
		return in.sval;
	}

	public static void main(String[] args) throws IOException {
		in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
		out = new PrintWriter(System.out);
		
		int n = nextInt();
		int[] q = new int[n];
		for (int i = 0; i < n; i++) q[i] = nextInt();
		int m = nextInt();
		int[][] g = new int[n][n];
		for (int[] a : g) Arrays.fill(a, Integer.MAX_VALUE);
		for (int i = 0; i < m; i++) {
			int a = nextInt()-1, b = nextInt()-1;
			g[a][b] = Math.min(g[a][b], nextInt());
		}
		
		int boss = -1, maxQ = Integer.MIN_VALUE;
		for (int i = 0; i < n; i++) 
			if (q[i] > maxQ) {
				maxQ = q[i];
				boss = i;
			}
		
		long ans = 0;
		for (int i = 0; i < n; i++) if (i != boss) {
			int best = Integer.MAX_VALUE;
			for (int j = 0; j < n; j++) best = Math.min(best, g[j][i]);
			if (best == Integer.MAX_VALUE) {
				out.println("-1");
				out.flush();
				return;
			}
			ans += best;
		}
		
		out.println(ans);
		
		out.flush();
	}
}
