#include<bits/stdc++.h>

using namespace std;

struct INIT{
    INIT(){
	ios::sync_with_stdio(false);
	cin.tie(0);
    }
}init;
typedef vector<int> V;
typedef vector<int> E;
typedef vector<E> Graph;
typedef long long LL;
typedef vector<LL> VL; 
void make_tree(int v, Graph &G, E &P, Graph &C, V& D,VL &sum) {
    for (auto& e : G[v]) {
	if (e!= P[v]) {
	    C[v].push_back(e);
	    D[e] = D[v]+1;
	    P[e] = v;
	    sum[e]+=sum[v];
	    make_tree(e, G, P, C, D,sum);
	}
    }
}

//lcaの準備
void build_PP(E& P,vector<V>& PP){
    int N = P.size();
    for(int i = 0; i < N; i++)PP[0][i] = P[i];
    for(int k = 0,f=1;f; k++){
	f=0;
	for(int i = 0; i < N; i++){
	    if(PP[k][i]<0)PP[k+1][i]=-1;
	    else {PP[k+1][i]=PP[k][PP[k][i]];f=1;}
	}
    }
}
int lca(int u,int v,V& D,vector<V> &PP){
	if(D[u] > D[v])swap(u,v);
	for(int k = 0,d;(d=D[v]-D[u]); k++)if((d >> k) & 1)v=PP[k][v];
	if(u==v)return v;
	for(int k = PP.size() - 1; k >=0 ; k--){
		if(PP[k][u]!=PP[k][v]){
			u=PP[k][u];
			v=PP[k][v];
		}
	}
	return PP[0][u];
}
#define rep(i,n) for(auto i=(n)*0;i<n;i++)

int main(){
    int N;
    cin>>N;
    Graph g(N+1);
    g[N].push_back(0);
    rep(i,N-1){
	int a,b;
	cin>>a>>b;
	g[a].push_back(b);
	g[b].push_back(a);
    }
    vector<V> pp(20,V(N+1,-1));
    Graph child(N+1);
    V p(N+1),depth(N+1);
    VL U(N+1);
    p[N]=-1;U[N]=0;depth[N]=0;
    rep(i,N)cin>>U[i];
    make_tree(N,g,p,child,depth,U);
    build_PP(p,pp);
    LL res=0;
    int M;
    cin>>M;
    rep(i,M){
	int a,b,c;
	cin>>a>>b>>c;
	int ca=lca(a,b,depth,pp);
	int cp=p[ca];
	res+=c*(U[a]+U[b]-U[ca]-U[cp]);
    }
    cout<<res<<endl;

    

}