#include<bits/stdc++.h>
using namespace std;
int dis[30005],hs[30005];
queue<int>qx,qh,qd;
int n,m,H;
vector<pair<int,int> >G[30005];
int ah[30005];
int main(){
//	freopen("game.in","r",stdin);
	scanf("%d%d%d",&n,&m,&H);
	for(int i=1;i<=n;i++)scanf("%d",&ah[i]);
	for(int i=1;i<=m;i++){
		int u,v,w;
		scanf("%d%d%d",&u,&v,&w);
		G[u].push_back(make_pair(v,w));
		G[v].push_back(make_pair(u,w));
	}
	qx.push(1);
	qh.push(H);
	qd.push(0);
	while(!qx.empty()){
		int f=qx.front();qx.pop();
		int h=qh.front();qh.pop();
		int d=qd.front();qd.pop();
		for(int i=0;i<G[f].size();i++)if(G[f][i].second<h){
			int v=G[f][i].first;
			int w=min((h-G[f][i].second+ah[v]),H);
			if(w>hs[v]){
				hs[v]=w;
				qx.push(v);
				qh.push(w);
				qd.push(d+1);
				if(v==n){
					printf("%d",d+1);
					return 0;
				}
			}
		}
	}
	printf("-1");
	return 0;
}