#include <vector>
#include <algorithm>
#include <iostream>
#include <set>

#define int long long
using namespace std;

struct edge {
    int to, w;

    edge(int to, int w) : to(to), w(w) {};
};

int n, m, s, f;
vector<vector<edge>> g;
vector<vector<int>> lim;
vector<int> dist;
const int INF = 1e9;
const int TL = 24 * 60;
const int VEHICLE = 3 * 1e6;

bool djikstra(int limit) {
    dist.assign(n, INF);
    dist[s] = 0;
    set<pair<int, int>> q;
    for (int v = 0; v < n; ++v) {
        q.insert({dist[v], v});
    }
    while (!q.empty()) {
        int now = (*q.begin()).second;
        q.erase(q.begin());
        for (auto u : g[now]) {
            if (lim[now][u.to] >= limit && dist[u.to] > dist[now] + u.w) {
                q.erase({dist[u.to], u.to});
                dist[u.to] = dist[now] + u.w;
                q.insert({dist[u.to], u.to});
            }
        }
    }
    return dist[f] <= TL;
}

signed main() {
//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stdout);
    cin >> n >> m;
    if (n == 1) {
        cout << 10 * (int) 1e6;
        return 0;
    }
    g.resize(n);
    lim.assign(n, vector<int>(n, INF));
    for (int _ = 0; _ < m; ++_) {
        int a, b, w_, l;
        cin >> a >> b >> w_ >> l;
        a--, b--;
        g[a].emplace_back(b, w_);
        g[b].emplace_back(a, w_);
        lim[a][b] = l;
    }
    s = 0, f = n - 1;
    int l = 0, r = INF;
    while (l + 1 < r) {
        m = (l + r) / 2;
        if (djikstra(VEHICLE + 100 * m)) {
            l = m;
        } else {
            r = m;
        }
    }
    cout << l;
    return 0;
}