#include<bits/stdc++.h>
using namespace std;
long long n,m,c[4005],f[4005];
long long nxt[4005],h[4005],to[4005],cnt,w[1005];
double dis[1005];
bool b[1005];
void add(int x,int y,int xx,int yy){
	cnt++;
	nxt[cnt]=h[x];
	h[x]=cnt;
	to[cnt]=y;
	c[cnt]=xx;
	f[cnt]=yy;
}
priority_queue<pair<double,long long>,vector<pair<double,long long> >,greater<pair<double,long long> > >q;
double check(int ft){
	for(int i=1;i<=n;i++){
		dis[i]=1e9;b[i]=0;
	}
	dis[1]=0;
	q.push(make_pair(0,1));
	while(!q.empty()){
 		long long t=q.top().second;
 		q.pop();
 		if(b[t]==1){
 			continue;
		}
 		b[t]=1;
 		for(long long i=h[t];i!=0;i=nxt[i]){
 			long long y=to[i];//cout<<ft<<endl;
			 //ft=min(ft,f[i]);//cout<<ft<<" "<<f[y]<<endl;;
 	//		printf("p:%f ft:%lld w:%f dis[y]:%f dis[t]:%f f[i]:%lld \n",p,ft,w,dis[y],dis[t],f[i],y); 
 			if(dis[y]>dis[t]+c[i]&&f[i]>=ft){
 				dis[y]=dis[t]+c[i];
 				q.push(make_pair(dis[y],y));
			}
		 }
	 }
	 return 1.0*ft/dis[n];
}
int main(){
	freopen("pump.in","r",stdin);
	freopen("pump.out","w",stdout);
	cin>>n>>m;
	for(int i=1;i<=m;i++){
		int x,y,xx,yy;
		cin>>x>>y>>xx>>yy;
		w[i]=yy;
		add(x,y,xx,yy);
		add(y,x,xx,yy);
	}
	int ans=0;
	for(int i=1;i<=m;i++){
		ans=max(ans,int(check(w[i])*1e6));
	}cout<<ans;
	return 0;
}