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 Hierarchy
{
	public static void main( String[] args ) throws Exception
	{
		BufferedReader reader = new BufferedReader( new InputStreamReader( System.in ) );
		PrintWriter pw = new PrintWriter( new OutputStreamWriter( System.out ) );
		
		int numEmployees = Integer.parseInt( reader.readLine() );
		int quals[] = new int[numEmployees];
		
		String line = reader.readLine();
		String[] split = line.split( "\\s+" );
		for( int i = 0; i < split.length; i++ )
			quals[i] = Integer.parseInt( split[i] );
		
		int numApps = Integer.parseInt( reader.readLine() );
		
		int costs[] = new int[numEmployees];
		for( int i = 0; i < numEmployees; i++ )
			costs[i] = Integer.MAX_VALUE;
			
		for( int i = 0; i < numApps; i++ )
		{
			line = reader.readLine();
			split = line.split( "\\s+" );
			
			int a = Integer.parseInt( split[0] );
			int b = Integer.parseInt( split[1] );
			int cost = Integer.parseInt( split[2] );
			
			if( cost < costs[b - 1] )
				costs[b - 1] = cost;
		}
		
		int totalCost = 0;
		int found = 0;
		for( int i = 0; i < numEmployees; i++ )
		{
			if( costs[i] == Integer.MAX_VALUE )
				found++;
			else
				totalCost += costs[i];
		}
		
		if( found == 1 )
			pw.println( totalCost );
		else
			pw.println( -1 );
		
		pw.close();
	}
}