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.InputStreamReader;

public class CF17B {

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int numEmployees = Integer.parseInt(br.readLine());

		int[] q = new int[numEmployees];
		String[] rLine = br.readLine().split(" ");

		for (int i=0;i<numEmployees;i++) {
			q[i] = Integer.parseInt(rLine[i]);
		}

		int numApps = Integer.parseInt(br.readLine());
		int[] applicants = new int[numApps];
		int[] toSupervise = new int[numApps];
		int[] cost = new int[numApps];

		for (int i=0;i<numApps;i++) {
			String[] tLine = br.readLine().split(" ");
			applicants[i] = Integer.parseInt(tLine[0]);
			toSupervise[i] = Integer.parseInt(tLine[1]);
			cost[i] = Integer.parseInt(tLine[2]);
		}

		int[] d = new int[numEmployees+1];
		for (int i=1;i<=numEmployees;i++) d[i] = 1000000000;
		for (int i=0;i<numApps;i++) {
			if (d[toSupervise[i]] > cost[i]) d[toSupervise[i]] = cost[i];
		}

		int count = 0;
		int sum = 0;
		for (int i=1;i<=numEmployees;i++) {
			if (d[i] == 1000000000) count++;
			else sum += d[i];
		}

		if (count == 1) System.out.println(sum);
		else System.out.println("-1");

	}
}