from heapq import *

n, m = map(int, input().split())
edges = [[] for _ in range(n)]
for _ in range(m):
    a, b, c = map(int, input().split())
    a -= 1
    b -= 1
    edges[a].append((b, c))
    edges[b].append((a, c))
T = list(map(int, input().split()))
inf = 1 << 60
dist = [[inf] * 1002 for _ in range(n)]
dist[0][0] = 0
hq = [(0, 0, 0)]
while hq:
    d, pos, p = heappop(hq)
    if dist[pos][p] < d:
        continue
    p += T[pos]
    p = min(p, 1001)
    d += T[pos]
    for npos, c in edges[pos]:
        tmp = d + c // p
        if dist[npos][p] > tmp:
            dist[npos][p] = tmp
            heappush(hq, (tmp, npos, p))
print(min(dist[-1]))