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.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) throws FileNotFoundException, IOException {
		InputReader in = new InputReader(new BufferedInputStream(System.in));
		PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));
		TaskB solver = new TaskB();
//		long t1 = System.currentTimeMillis();
		solver.solve(1, in, out);
		out.flush();
//		long t2 = System.currentTimeMillis();
//		System.err.println(t2 - t1);
		out.close();

	}
}

class Pos implements Comparable<Pos> {
	int x;
	int y;
	long val;

	public Pos(int x, int y, long val) {
		this.x = x;
		this.y = y;
		this.val = val;
	}

	public int compareTo(Pos p) {
		if (val == p.val) {
			if (x == p.x)
				return Integer.compare(y, p.y);
			return Integer.compare(x, p.x);
		}
		return Long.compare(val, p.val);
	}

}

class Pair implements Comparable<Pair> {
	int fir;
	int sec;

	Pair(int fir, int sec) {
		this.fir = fir;
		this.sec = sec;
	}

	public int compareTo(Pair p) {
		return Integer.compare(sec, p.sec);
	}
}

class TaskB {

	int INF = (int) 1e9;
	int id[];
	int sz[];
	int sup[];

	void solve(int testNumber, InputReader in, PrintWriter pw) throws IOException {
		int n = in.nextInt();
		for (int i = 0; i < n; ++i)
			in.nextInt();
		int m = in.nextInt();
		int min[] = new int[n];
		Arrays.fill(min, INF);
		for (int i = 0; i < m; ++i) {
			int u = in.nextInt() - 1;
			int v = in.nextInt() - 1;
			int w = in.nextInt();
			min[v] = Math.min(min[v], w);
		}
		boolean root = false;
		long ans = 0;
		for (int i = 0; i < n; ++i) {
			if (min[i] == INF) {
				if (root) {
					pw.println(-1);
					return;
				} else {
					root = true;
				}
			} else {
				ans += min[i];
			}
		}
		pw.println(ans);
	}

	int find(int x) {
		int p = x;
		while (id[p] != p) {
			p = id[p];
		}
		int par = p;
		p = x;
//		 path compression
		while (id[p] != p) {
			int tmp = id[p];
			id[p] = par;
			p = tmp;
		}
		return par;
	}

	boolean union(int p, int q) {
		int root1 = find(p);
		int root2 = find(q);
		if (sup[root1] > 0 && sup[root2] > 0)
			return false;
		if (root1 == root2)
			return false;
		if (sz[root1] < sz[root2]) {
			sz[root2] += sz[root1];
			id[root1] = root2;
			sup[root1]++;
		} else {
			sz[root1] += sz[root2];
			id[root2] = root1;
			sup[root2]++;
		}
		return true;
	}

	long gcd(long x, long y) {
		if (y == 0)
			return x;
		return gcd(y, x % y);
	}

	long pow(int n, int m) {
		if (m == 0)
			return 1;
		long ans = pow(n, m / 2);
		ans = (ans * ans);
		if (m % 2 == 1) {
			ans = (ans * n);
		}
		return ans;
	}

	double pow(double n, int m) {
		if (m == 0)
			return 1;
		double ans = pow(n, m / 2);
		ans = (ans * ans);
		if (m % 2 == 1) {
			ans = (ans * n);
		}
		return ans;
	}
}

class InputReader {
	BufferedReader br;
	StringTokenizer st;

	public InputReader(InputStream in) {
		br = new BufferedReader(new InputStreamReader(in));
		st = null;
	}

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

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

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

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