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 CF17B {
	public static void main(String[] args) throws IOException {
		in.init(System.in);
		int n = in.nextInt(); 
		for(int i = 0; i < n; i ++)
			in.nextInt();
		int m = in.nextInt();
		int ans = 0;
		int[] min = new int[n];
		Arrays.fill(min,  987654321);
		for(int i = 0; i < m; i ++)
		{
			int a = in.nextInt()-1;
			int b = in.nextInt()-1;
			int c = in.nextInt();
			min[b]=Math.min(min[b], c);
		}
		int z = 0;
		for(int i = 0; i < n; i ++)
		{
			if(min[i]==987654321)
				z++;
			else ans+=min[i];
		}
		System.out.println(z>1?"-1":ans);
	}
	public static class in {
		static BufferedReader reader;
		static StringTokenizer tokenizer;
		static void init(InputStream in) {
			reader = new BufferedReader(
			new InputStreamReader(in));
			tokenizer = new StringTokenizer("");
		}

		static String next() throws IOException {
			while (!tokenizer.hasMoreTokens()) {
				tokenizer = new StringTokenizer(
				reader.readLine());
			}
			return tokenizer.nextToken();
		}
		static int nextInt() throws IOException {
			return Integer.parseInt(next());
		}
		static double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}
		static long nextLong() throws IOException {
			return Long.parseLong(next());
		}
	}
}
