#include<bits/stdc++.h>
using namespace std;
int n,m,k,a[30001],b[30001];
vector<pair<int,int>>e[30001];
struct node{int x,y,z;};
queue<node>q;
int main() {
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	cin>>n>>m>>k;
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=1,u,v,w;i<=m;i++)cin>>u>>v>>w,e[u].push_back({v,w}),e[v].push_back({u,w});
	q.push({1,k,0});
	while(!q.empty()){
		node t1=q.front();q.pop();
		int u=t1.x,h=t1.y,d=t1.z;
		if(u==n)return cout<<d,0;
		for(auto ee:e[u]){
			int v=ee.first,w=ee.second;
			if(h<=w)continue;
			int ne=min(k,h-w+a[v]);
			if(ne<=b[v])continue;
			q.push({v,ne,d+1});
			b[v]=ne;
		}
	}
	return cout<<-1,0;
}