import sys
input = sys.stdin.readline


class LowestCommonAncestor:
    def __init__(self, n):
        self._n = n
        self._logn = 0
        v = 1
        while v <= self._n:
            v *= 2
            self._logn += 1
        self._depth = [0] * self._n
        self._distance = [0] * self._n
        self._ancestor = [[-1] * self._n for _ in range(self._logn)]
        self._G = [[] for i in range(self._n)]

    def add_edge(self, u, v, w=1):
        self._G[u].append((v, w))
        self._G[v].append((u, w))

    def build(self, root=0):
        stack = [root]
        self._distance[root] = U[root]
        while stack:
            cur = stack.pop()
            for nex, _ in self._G[cur]:
                if self._ancestor[0][nex] != cur and self._ancestor[0][cur] != nex:
                    self._ancestor[0][nex] = cur
                    self._depth[nex] = self._depth[cur] + 1
                    self._distance[nex] = self._distance[cur] + U[nex]
                    stack.append(nex)

        for k in range(1, self._logn):
            for i in range(self._n):
                if self._ancestor[k - 1][i] == -1:
                    self._ancestor[k][i] = -1
                else:
                    self._ancestor[k][i] = self._ancestor[k -
                                                          1][self._ancestor[k - 1][i]]

    def lca(self, u, v):
        if self._depth[u] > self._depth[v]:
            u, v = v, u

        for k in range(self._logn - 1, -1, -1):
            if ((self._depth[v] - self._depth[u]) >> k) & 1:
                v = self._ancestor[k][v]

        if u == v:
            return u

        for k in range(self._logn - 1, -1, -1):
            if self._ancestor[k][u] != self._ancestor[k][v]:
                u = self._ancestor[k][u]
                v = self._ancestor[k][v]

        return self._ancestor[0][u]

    def distance(self, u, v):
        return self._distance[u] + self._distance[v] - 2 * self._distance[self.lca(u, v)] + U[self.lca(u, v)]


N = int(input())
G = LowestCommonAncestor(N)
for i in range(N - 1):
    u, v = map(int, input().split())
    G.add_edge(u, v)
    G.add_edge(v, u)

U = [0] * N
for i in range(N):
    U[i] = int(input())

G.build(0)

M = int(input())
ans = 0
for _ in range(M):
    A, B, C = map(int, input().split())
    ans += C * G.distance(A, B)

print(ans)