from heapq import heappop as pop, heappush as push

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

queue = [(0, 0)]
ans = [-1]*N

while queue:
    c, v = pop(queue)
    if ans[v] != -1:
        continue
    ans[v] = c

    for u, c_ in edges[v]:
        if ans[u] != -1:
            continue
        push(queue, (c+c_, u))
print((ans[-1]-1)//X+1)