using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

class Magatro
{
    static int N, M;
    static List<int>[] Root;
    static int[] U;
    static int[] toZero;
    static List<int>[] R;
    static void Main()
    {
        Read();
        int cnt = 0;
        int m = int.Parse(Console.ReadLine());
        for(int i = 0; i < m; i++)
        {
            int[] abc = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
            int c = calc(abc[0], abc[1]) * abc[2];
          //  Console.WriteLine(c);
            cnt += c;
        }
        Console.WriteLine(cnt);
    }
    static int calc(int s, int g)
    {

        int sc = R[s].Count, gc = R[g].Count ;
        int cvill = 0;
        for(int i=0; ; i++)
        {
            if (i<sc && i<gc)
            {
                if (R[s][i]==R[g][i])
                {
                    cvill = R[s][i];
                }
                else
                {
                    break;
                }
            }
            else
            {
                break;
            }
        }
        return toZero[s] + toZero[g] - toZero[cvill] - toZero[cvill]+U[cvill];
    }
    static void Read()
    {
        N = int.Parse(Console.ReadLine());
        Root = new List<int>[N];
     
        for (int i = 0; i < N; i++)
        {
            Root[i] = new List<int>();
        }
        for (int i = 0; i < N - 1; i++)
        {
            string[] s = Console.ReadLine().Split(' ');
            int a = int.Parse(s[0]);
            int b = int.Parse(s[1]);
            Root[a].Add(b);
            Root[b].Add(a);
        }
        U = new int[N];
        R = new List<int>[N];
        for (int i = 0; i < N; i++)
        {
            R[i] = new List<int>();
            U[i] = int.Parse(Console.ReadLine());
        }
    
        toZero = new int[N];
        bool[] ed = new bool[N];
        Queue<int> q = new Queue<int>();
        q.Enqueue(0);
        toZero[0] = U[0];
        ed[0] = true;
        R[0].Add(0);
        while (q.Count > 0)
        {
            int w = q.Dequeue();
            for(int i = 0; i < Root[w].Count; i++)
            {
                int e = Root[w][i];
                if (!ed[e])
                {
                    q.Enqueue(e);
                    ed[e] = true;
                    toZero[e] = toZero[w] + U[e];
                    R[e] = R[w].ToList();
                    R[e].Add(e);
                }
            }
        }
    }
}