#include "bits/stdc++.h"
using namespace std;

#define REP(i, n) for(ll i = 0;i < n;i++)
#define REPR(i, n) for(ll i = n;i >= 0;i--)
#define FOR(i, m, n) for(ll i = m;i < n;i++)
#define FORR(i, m, n) for(ll i = m;i >= n;i--)
#define REPO(i, n) for(ll i = 1;i <= n;i++)
#define ll long long
#define INF (ll)1ll << 60
#define MINF (-1 * INF)
#define ALL(n) n.begin(),n.end()
#define MOD (ll)1000000007
#define P pair<ll, ll>

ll d[210000]; 
struct edge { ll to, cost; };
vector<edge> g[210000];
void dijkstra(ll a) {
	priority_queue<P, vector<P>, greater<P> > q;
	fill(d, d + 210000, INF);
	d[a] = 0;
	q.push(P(0, a));
	while (!q.empty()) {
		P p = q.top();
		q.pop();
		ll v = p.second;
		if (d[v] < p.first) continue;
		REP(i, g[v].size()) {
			edge e = g[v][i];
			if (d[e.to] > d[v] + e.cost) {
				d[e.to] = d[v] + e.cost;
				q.push(P(d[e.to], e.to));
			}
		}
	}
}
int main(){
    ll n, m, x;
    cin >> n >> m >> x;
    REP(i, m){
        ll a, b, c, d;
        cin >> a >> b >> c >> d;
        a--; b--;
        g[a].push_back({b, c + x * d});
        g[b].push_back({a, c + x * d});
    }
    dijkstra(0);
    cout << (d[n - 1] + x - 1) / x << endl;
}