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;


 public class hello
 {
      public static void main(String args[]) throws IOException
      {
          BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
          ArrayList<Integer>b=new ArrayList<Integer>();
          ArrayList<Integer>cost=new ArrayList<Integer>();
          int n=Integer.parseInt(br.readLine());
          String qual=br.readLine();
          int num=Integer.parseInt(br.readLine());
          for(int i=0;i<num;i++)
          {
              String s=br.readLine();
              String[] inp=s.split(" ");
              if(!b.contains(Integer.parseInt(inp[1])))
              {
                  b.add(Integer.parseInt(inp[1]));
                  cost.add(Integer.parseInt(inp[2]));
              }  
              else
              {
                  int index=b.indexOf(Integer.parseInt(inp[1]));
                  if(cost.get(index)>Integer.parseInt(inp[2]))
                  {
                      cost.set(index,Integer.parseInt(inp[2]));
                  }
              }
          }
          if(b.size()==n-1)
          {
              int sum=0;
              for(int i=0;i<cost.size();i++)
              {
                  sum+=cost.get(i);
              }
              System.out.println(sum);
          }
          else
          {
              System.out.println("-1");
          }
      }
 }    