> #include<cstdio>
> #include<vector>
> #include<iostream>
> #include<cstring>
> using namespace std;
> const int N = 1009 ;
> vector<int> G[N];
> double mp[N][N],dis[N],co[N][N];
> bool vis[N];
> bool flag = false ;
> void f(int n){
> 	int h = n ;
> 	while(h--)
> 	{
> 		int max_p ;
> 		double max_d = 0 ;
> 		for(int i = 1 ; i <= n ; ++ i)
> 		{
> 			if(!vis[i] && dis[i] > max_d ){
> 				max_d = dis[max_p = i];
> 			}
> 		}
> 		vis[max_p] = true ;
> 		int u = max_p ;
> 		for(int i = 0 ; i< G[u].size() ;++ i ){
> 			int v = G[u][i];
> 			if(vis[v]) continue;
> 			dis[v] = max(dis[v],(dis[u]-co[u][v])*mp[u][v]);
> 		}
> 	}
> 	return ; 
> }
> void g (int n){
> 	for(int i = 1 ; i <= n ; ++ i){
> 		for(int j = 1 ; j <= n ; ++ j)
> 		{
> 			if(i==j) continue ;
> 			if(dis[j] < (dis[i]-co[i][j])*mp[i][j] )
> 			{
> 				flag = true ;
> 				return ;
> 			}
> 		}
> 	}
> 	return ;
> }
> int main (){
> 	int n,m,s;
> 	double v ;
> 	scanf("%d%d%d%lf",&n,&m,&s,&v);
> 	for(int i = 1 ; i <= m ; ++ i){
> 		int a,b;
> 		double e1,c1,e2,c2;
> 		scanf("%d%d%lf%lf%lf%lf",&a,&b,&e1,&c1,&e2,&c2);
> 		mp[a][b] = e1,mp[b][a] = e2; 
> 		co[a][b] = c1,co[b][a] = c2;
> 		G[a].push_back(b),G[b].push_back(a);
> 	}
> 	dis[s] = v ; 
> 	//vis[s] = true ;
> 	f(n);
> 	g(n);
> 	if(flag) cout<<"YES"<<endl;
> 	else cout<<"NO"<<endl;
> 	return 0 ;
> }