from heapq import *
INF = 10**18
def dijkstra(g, s, n):
    dist = [INF]*n
    hq = [(0, s)]
    dist[s] = 0
    while hq:
        d, v = heappop(hq)
        if dist[v]!=d:
            continue
        for to, c in g[v]:
            if dist[v] + c < dist[to]:
                dist[to] = dist[v] + c
                heappush(hq, (dist[to], to))
    return dist
from math import ceil
n, m, x = list(map(int, input().split()))
g = [[] for _ in range(n)]

for i in range(m):
    u,v,c,t = list(map(int, input().split()))
    u -= 1
    v -= 1
    g[u].append((v,t+c/x))
    g[v].append((u,t+c/x))

dist = dijkstra(g, 0, n)
if dist[-1] == INF:
    print(-1)
else:
    print(ceil(dist[-1]))