#include<cstdio>
#include<iostream>
#include<queue>
#include<cstring>
using namespace std;
int n,m,cnt,ans;
int to[2005],h[2005],nxt[2005],val1[2005],val2[2005];
void add(int u,int v,int w1,int w2){
	to[++cnt]=v;
	val1[cnt]=w1;
	val2[cnt]=w2;
	nxt[cnt]=h[u];
	h[u]=cnt;
}
bool vis[1005];
int dis[1005];
priority_queue<pair<int,int> >q;
int dijkstra(int limit){
	memset(vis,0,sizeof(vis));
	memset(dis,0x3f,sizeof(dis));
	dis[1]=0;
	q.push(make_pair(0,1));
	while(!q.empty()){
		int u=q.top().second;
		q.pop();
		if(vis[u])continue;
		vis[u]=1;
		for(int i=h[u];i;i=nxt[i]){
			int v=to[i];
			if(val2[i]>=limit&&dis[v]>dis[u]+val1[i]){
				dis[v]=dis[u]+val1[i];
				q.push(make_pair(-dis[v],v));
			}
		}
	}
	return dis[n];
}
int main(){
	freopen("pump.in","r",stdin);
	freopen("pump.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;i++){
		int a,b,c,f;
		scanf("%d%d%d%d",&a,&b,&c,&f);
		add(a,b,c,f);
		add(b,a,c,f);
	}
	for(int i=1;i<=2*m;i++){
		ans=max(ans,(int)(val2[i]*1e6/dijkstra(val2[i])));
	}
	printf("%d",ans);
	return 0;
}