import heapq
inf = 1 << 61
def dijkstra(s, n, edge):
    dist = [inf]*n
    dist[s] = 0
    hq = [[0,s]]
    heapq.heapify(hq)
    while len(hq) > 0:
        d,i = heapq.heappop(hq)
        if dist[i] < d:
            continue
        for j,d_1 in edge[i]:
            if dist[j] > (dist[i] + d_1):
                dist[j] = dist[i] + d_1
                heapq.heappush(hq, [dist[j],j])
    return dist

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

dist = dijkstra(0,N,G)
if dist[N-1] == inf:
  print(-1)
  exit()
ans = dist[N-1] // X
if dist[N-1] % X:
  ans += 1
print(ans)