#include <cstdio>
#include <vector>
#include <queue>
using namespace std;
const int MAXN=10005;

typedef long long LL;

struct Node
{
	int v,w;
	Node *next;
	Node(int a,int b,Node *c):v(a),w(b),next(c){}
}*adj[MAXN];

inline void add(int u,int v,int w)
{
	adj[u]=new Node(v,w,adj[u]);
	adj[v]=new Node(u,w,adj[v]);
}

int N,M,S,T,V,re=0x7fffffff;
int f[MAXN];

bool vis[MAXN];
void dfs(int u,int fee,LL pat)
{
	if (fee>=re)
		return ;
	if (u==T)
	{
		re=fee;
		return ;
	}
	vis[u]=true;
	for(Node *p=adj[u];p;p=p->next)
		if (!vis[p->v]&&pat+p->w<=V)
			dfs(p->v,max(fee,f[p->v]),pat+p->w);
	vis[u]=false;
}

int main()
{
	freopen("cost.in","r",stdin);
	freopen("cost.out","w",stdout);
	scanf("%d%d%d%d%d",&N,&M,&S,&T,&V);
	for(int i=1;i<=N;i++)
		scanf("%d",f+i);
	while(M--)
	{
		int a,b,c;
		scanf("%d%d%d",&a,&b,&c);
		add(a,b,c);
	}
	dfs(S,f[S],0);
	if (re==0x7fffffff) printf("%d\n",-1);
	else printf("%d\n",re);
	return 0;
}