#include <iostream>#include <cstring>#define eps 1e-8#define M 100000using namespace std;struct vertex{ double r; double c; int u; int v;}ver[10000];int k,n;double node[110],v;bool BF(int s){ int i,j; for(i = 0;i < n;i ++) { for(j = 0;j < k;j ++) { if(node[ver[j].v] < (node[ver[j].u] - ver[j].c) * ver[j].r) { node[ver[j].v] = (node[ver[j].u] - ver[j].c) * ver[j].r; } } } if(node[s] > v) return 1; for(j = 0;j < k;j ++) { if(node[ver[j].v]+eps< (node[ver[j].u] - ver[j].c) * ver[j].r) return 1; } return 0;}int main(){ int m,s,i,j,l,r; double rab,cab,rba,cba; while(cin>>n>>m>>s>>v) { k = 0; for(i = 0;i < m;i ++){ cin>>l>>r>>rab>>cab>>rba>>cba; ver[k].u = l;ver[k].v = r; ver[k].r = rab;ver[k].c = cab; k++; ver[k].u = r;ver[k].v = l; ver[k].r = rba;ver[k].c = cba; k++; } for(i = 0;i <= n;i ++) node[i] = 0; node[s] = v; if(BF(s) == 1) cout<<"YES"<<endl; else cout<<"NO"<<endl; } return 0;}
