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.
public class Driver {

	static final int MAX = 1000001;
	static int n, m, a, b, c, sum;
	static int[] cost;
	static String[] values;
	
	public static void main(String[] args) throws java.io.IOException {
		java.io.InputStreamReader isr = new java.io.InputStreamReader(System.in);
		java.io.BufferedReader in = new java.io.BufferedReader(isr);
		
		n = Integer.parseInt(in.readLine());
		cost = new int[n];
		for (int i = 0; i < n; i++) {
			cost[i] = MAX;
		}
		in.readLine();
		m = Integer.parseInt(in.readLine());
		
		if (m < n-1) {
			System.out.println("-1");
			in.close();
			return;
		}
		
		for (int i = 0; i < m; i++) {
			values = in.readLine().split(" ");
			a = Integer.parseInt(values[0]);
			b = Integer.parseInt(values[1]);
			c = Integer.parseInt(values[2]);
			
			if (cost[b-1] > c) {
				cost[b-1] = c;
			}
		}
		int roots = 0;
		sum = 0;
		for (int i = 0; i < n; i++) {
			if (cost[i] == MAX) {
				roots++;
				if (roots > 1) {
					sum = -1;
					break;
				}
			} else {
				sum += cost[i];
			}
		}
		System.out.println(sum);
		in.close();
	}
}