#include <iostream>
#include <queue>
#include <vector>
using namespace std;
 
struct boil{
	int mass=0;
	int len=0;
	char n/*new*/='y';//yes
	char visit='n';//no
	vector <int> link;
	vector <int> dis;
};
 
int main() {
	int N,M,B,C;
	cin>>N>>M>>B>>C;
	boil A[N];
	int need;
	for(int i=0;i<N;i++){
		cin>>A[i].mass;
		if(A[i].mass<B)need=i;
	}
	int a,b,s;
	while(cin>>a>>b>>s){
		a--;
		b--;
		A[a].link.push_back(b);
		A[a].dis.push_back(s);
		A[b].link.push_back(a);
		A[b].dis.push_back(s);
	}
	queue <int> A_tmp;
	A_tmp.push(need);
	A[need].n='n';
	int ans=0;
	while(!(A_tmp.empty())){
		int u=A_tmp.front();
		A_tmp.pop();
		A[u].visit='y';
		for(int i=0;i<A[u].link.size();i++){
			if(A[A[u].link[i]].visit=='n')
				A_tmp.push(A[u].link[i]);
			if(A[A[u].link[i]].len>A[u].len+A[u].dis[i] || A[A[u].link[i]].n=='y'){
				A[A[u].link[i]].len=A[u].len+A[u].dis[i];
				A[A[u].link[i]].n='n';
			}
		}
	}
	while(A[need].mass<B){
		int m=0;
		for(int i=0; i<N;i++){
			if((A[i].len<A[m].len|| A[m].mass<=B) && i!=need && A[i].mass>B)
				m=i;
		}
		if(A[need].mass+(A[m].mass-B)<=B){
			ans+=A[m].len*(A[m].mass-B);
			A[need].mass+=A[m].mass-B;
			A[m].mass=B;
		}
		else{
			ans+=A[m].len*(B-A[need].mass);
			int b=B-A[need].mass;
			A[need].mass=B;
			A[m].mass-=B-A[need].mass;
		}
	}
	cout<<ans*C;
	return 0;
}

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NSAgIDUgICA0ICAgNgo1ICA0ICA4ICAxICA2CjEgIDIgIDMKMiAgMyAgNQoyICA0ICAyCjMgIDQgIDYKMyAgNSAgNA==

5   5   4   6
5  4  8  1  6
1  2  3
2  3  5
2  4  2
3  4  6
3  5  4