#include<bits/stdc++.h> using namespace std; int hea[620001],tot,d[600021],v[620001]; int n,m,s,t,L; priority_queue< pair<int,int> > q; struct Edge{ int next,to,dis; }edge[620001]; //vector<int>vec[] void add(int x,int y,int z) { edge[++tot].next=hea[x]; edge[tot].to=y; edge[tot].dis=z; hea[x]=tot; } int main() { scanf("%d%d%d%d%d",&n,&m,&L,&s,&t); for(int i=1;i<=m;i++) { int x,y,z; scanf("%d%d%d",&x,&y,&z); add(x,y,z); add(y,x,z); } memset(d,0x3f,sizeof(d)); memset(v,0,sizeof(v)); d[s]=0;q.push(make_pair(0,s)); while(!q.empty()) { int x=q.top().second;q.pop(); if(v[x]) continue; v[x]=1; for(int i=hea[x];i;i=edge[i].next) { int y=edge[i].to; if(d[y]>d[x]+edge[i].dis) { d[y]=d[x]+edge[i].dis; q.push(make_pair(-d[y],y)); } } } // printf("%d\n",d[t]); if(d[t]>L) puts("NO"),exit(0); else puts("YES"); return 0; }