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.util.*;
import java.io.*;
public class pt{ 
  
public static void main(String[] args)throws IOException { 

PrintWriter out = new PrintWriter(System.out);
  int n = ni();
  for(int i=0;i<n;i++){ int x = ni();}

  int a[] = new int[n];
  int max= 99999999;
  Arrays.fill(a,max);
  int m = ni();

for(int i=0;i<m;i++){

   int s = ni()-1;
   int d = ni()-1;
   int c = ni();
   a[d] = Math.min(a[d],c);
}                  
int c=0;
long ans=0;
for(int i=0;i<n;i++)
  if(a[i]==max)c++;
  else
    ans = ans+a[i];
  
if(c>1) ans=-1;

out.println(ans);
      out.flush();
} 

              static int mod=1000000007;
              static long pow(long a,long b){
                       long ans=1;
                      while(b>0){
                          if(b%2==1)
                              ans=(ans*a);
                              a=(a*a)%mod;
                              b=b/2;
                      }
                    return(ans);
                }
             static long gcd(long a,long b){
                           if(b%a==0)
                               return(a);
                               return(gcd(b%a,a));
              }
            static long lcm(long a,long b){
                         return ((a*b)/gcd(a,b));
               }
              static void Fact(long a[],long m){
                              a[0]=1;
                           for(int i=1;i<a.length;i++)
                                   a[i]=(i*a[i-1])%m;

                      }
            /*  static void Fact_Inv(long a[],long F[],long m){

                                 int n =a.length;
                                     a[n-1]=Fermat(F[n-1],m);
                                 for(int i=n-2;i>=0;i--)
                                        a[i]=((i+1)*a[i+1])%m;
                     
               static  long d, x, y;
              static void extendedEuclid(long A, long B) {
                            if(B == 0) {
                                  d = A;
                                  x = 1;
                                  y = 0;
                              }
                           else {
                                extendedEuclid(B, A%B);
                                 long temp = x;
                                  x = y;
                                 y = temp - (A/B)*y;
                            }
                     } */
                 /*static class pair implements Comparable<pair>{
                       int x,y;
                      pair(int a,int b){
                             x=a;
                             y=b;
                       }
                     public int compareTo(pair p1)
                           { return((p1.x-p1.y)-(this.x-this.y));}
          
                   public boolean equals(Object obj) {
                         if (this == obj)
                                return true;
                        if (obj == null)
                                return false;
                        if (getClass() != obj.getClass())
                                return false;
                         pair other = (pair) obj;
                          if (x != other.x)
                                  return false;
                          if (y != other.y)
                                  return false;
                            return true;
                      }
                      @Override
                 public int hashCode() {
                      return(x-y);
                   } 
          }   */

      static void addEdge(LinkedList<Integer> adjList[],int s,int d){
                             adjList[s].add(d);
                             adjList[d].add(s);
              }
       static int abs(char x,char y)
                   { return(Math.abs(x-y));}
        static long min(long x,long y){
                     return(Math.min(x,y));
                 }
        static long max(long a,long b){
                        return Math.max(a,b);
                  }    
    static FastReader sc=new FastReader(); 
 
      static int ni(){
                 int x = sc.nextInt();
                 return(x);
        }
      static long nl(){
              long x = sc.nextLong();
              return(x);
         }
      static String n(){
                 String str = sc.next();
                     return(str);
       }
     static String ns(){
                 String str = sc.nextLine();
                   return(str);
      }
     static double nd(){
               double d = sc.nextDouble();
                 return(d);
       }
  static class FastReader 
    { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() 
        { 
            br = new BufferedReader(new
                     InputStreamReader(System.in)); 
        } 
  
        String next() 
        { 
            while (st == null || !st.hasMoreElements()) 
            { 
                try
                { 
                    st = new StringTokenizer(br.readLine()); 
                } 
                catch (IOException  e) 
                { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() 
        { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() 
        { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() 
        { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() 
        { 
            String str = ""; 
            try
            { 
                str = br.readLine(); 
            } 
            catch (IOException e) 
            { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } 
}