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.ArrayList;
import java.util.StringTokenizer;

public class CF0017B_Hierarchy {
	static class Scanner {
		BufferedReader br;
		StringTokenizer st;

		public Scanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
	}

	static class Employee {
		int id;
		int qual;
		ArrayList<Employee> manager;
		ArrayList<Integer> cost;

		public Employee(int id, int qual) {
			this.id = id;
			this.qual = qual;
			manager = new ArrayList<>();
			cost = new ArrayList<>();
		}

//		@Override
//		public int compareTo(Employee o) {
//			return qual - o.qual;
//		}

	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner = new Scanner();
		int n = scanner.nextInt();
		Employee[] emps = new Employee[n];
		for (int i = 0; i < n; i++) {
			emps[i] = new Employee(i, scanner.nextInt());
		}
		int q = scanner.nextInt();
		for (int i = 0; i < q; i++) {
			int a = scanner.nextInt() - 1;
			int b = scanner.nextInt() - 1;
			int cost = scanner.nextInt();
			emps[b].manager.add(emps[a]);
			emps[b].cost.add(cost);
		}
		int cost = 0;
		boolean[] visited = new boolean[n];
	
		Employee ae = new Employee(-1, -1);
		for (int i = 0; i < n; i++) {
			if (!visited[i]) {
				if (emps[i].qual > ae.qual)
					ae = emps[i];
			}
		}
		visited[ae.id] = true;
		
		
		
		for (int f = 1; f < n; f++) {
			Employee e = new Employee(-1, -1);
			for (int i = 0; i < n; i++) {
				if (!visited[i]) {
					if (emps[i].qual > e.qual)
						e = emps[i];
				}
			}
			visited[e.id] = true;
			if (e.manager.size() == 0) {
				System.out.println(-1);
				return;
			}
			int localCost = Integer.MAX_VALUE;
			for (int i = 0; i < e.cost.size(); i++) {
				localCost = Math.min(localCost, e.cost.get(i));
			}
			cost+=localCost;
		}
		System.out.println(cost);
	}

}
