N,M,X = map(int,input().split())

G = [[] for _ in range(N)]
for _ in range(M):
    u,v,c,t = map(int,input().split())
    u -= 1
    v -= 1
    G[u].append((v,c + t * X))
    G[v].append((u,c + t * X))

import heapq
q = [(0,0)]

inf = 10 ** 20

dist = [inf] * N
dist[0] = 0
while q:
    d,now = heapq.heappop(q)
    if d > dist[now]:continue
    for v,c in G[now]:
        if dist[v] > d + c:
            dist[v] = d + c
            heapq.heappush(q,(d + c,v))
if dist[-1] == inf:
    print(-1)
else:
    k = dist[-1]
    print((k + X - 1) // X)