/// Milk Pumping Gold USACO
/// Author: PmQwerty
#include<bits/stdc++.h>
using namespace std;
const int MAXN = 1010;
const int INF = 1e9 + 7;
struct Edge{
    int u;
    int w;
    int f;
    Edge(){
    }
    Edge(int u, int w, int f): u(u), w(w), f(f) {}
};
vector<Edge> a[MAXN];
int n, m;
int d[MAXN];
int dijkstra(int f){
    priority_queue<pair<int, int>> pq;
    for (int i = 0; i < n; i++){
         d[i] = INF;
    }
    d[0] = 0;
    pq.push({0, 0});
    while (!pq.empty()){
        int u = pq.top().second;
        int w = pq.top().first;
        pq.pop();
        for (Edge v: a[u]){
             if (v.f < f) continue;
             if (d[v.u] > w + v.w){
                 d[v.u] = w + v.w;
                 pq.push({d[v.u], v.u});
             }
        }
    }
    return (d[n - 1] == INF ? -1 : d[n - 1]);
}
int main(){
    //freopen("pump.in", "r", stdin);
    //freopen("pump.out", "w", stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m;
    vector<int> flows;
    for (int i = 1; i <= m; i++){
         int u, v, c, f;
         cin >> u >> v >> c >> f;
         flows.push_back(f);
         u--;
         v--;
         a[u].push_back(Edge(v, c, f));
         a[v].push_back(Edge(u, c, f));
    }
    int ans = -1;
    for (int f: flows){
         int cur = dijkstra(f);
         if (cur == -1) continue;
         double r = f * 1.0 / cur;
         ans = max(ans, (int)(r * 1e6));
    }
    cout << ans << '\n';
}
 

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