N,M,X = map(int, input().split())
edge = [[] for i in range(N)]

for i in range(M):
    u,v,c,t = map(int, input().split())
    u-=1;v-=1
    edge[u].append((v,(t+c/X)*10**12))
    edge[v].append((u,(t+c/X)*10**12))

from heapq import *
INF = 10**24
def dijkstra(N, edge, s):
    dist = [INF] * N
    que = [(0, s)]
    dist[s] = 0
    while que:
        c, v = heappop(que)
        if dist[v] < c:
            continue
        for t, cost in edge[v]:
            if dist[v] + cost < dist[t]:
                dist[t] = dist[v] + cost
                heappush(que, (dist[t], t))
    return dist
import math
d = dijkstra(N,edge,0)
ans = d[-1]
print(math.ceil(ans/10**12) if ans != INF else -1)