#include <bits/stdc++.h>
using namespace std;
int n, m;
struct Edge
{
    int v, w, f;
};
vector<Edge> e[1010];
struct Point
{
    int id, dis;
};
bool operator<(Point a, Point b)
{
    return a.dis > b.dis;
}
int dis[1010];
bool vis[1010];

priority_queue<Point> q;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n >> m;
    int maxf = 0, minf = 0x3f3f3f3f;
    for (int i = 1; i <= m; i++)
    {
        int u, v, w, f;
        cin >> u >> v >> w >> f;
        e[u].push_back((Edge){v, w, f});
        e[v].push_back((Edge){u, w, f});
        minf = min(minf, f);
        maxf = max(maxf, f);
    }
    int ans = 0;
    for (int i = minf; i <= maxf; i++)
    {
        // 最短路

        // 初始化
        while (!q.empty())
        {
            q.pop();
            // 
            //cout << " ";
        }
        memset(dis, 0x3f, sizeof(dis));
        memset(vis, false, sizeof(vis));
        dis[1] = 0;
        q.push((Point){1, 0});
        // dijkstra
        for (int t = 1; t < n; t++)
        {
            while (!q.empty() && vis[q.top().id])
            {
                q.pop();
            }
            if (q.empty())
                break;
            int u = q.top().id;
            vis[u] = true;
            for (int j = 0; j < e[u].size(); j++)
            {
                int f = e[u][j].f;
                if (f < i)
                    continue;
                int v = e[u][j].v;
                if (vis[v])
                    continue;
                int w = e[u][j].w;
                if (dis[v] > dis[u] + w)
                {
                    dis[v] = dis[u] + w;
                    q.push((Point){v, dis[v]});
                }
            }
        }
        if (dis[n] == 0x3f3f3f3f)
        {
            continue;
        }
        double res = 1e6*i / dis[n];
        ans = max(ans, (int)res);
    }
    cout << ans;
    return 0;
}