N,M = map(int,input().split())
G = [[] for _ in range(N)]
for _ in range(M):
    a,b,c = map(int,input().split())
    a -= 1
    b -= 1
    G[a].append((b,c))
    G[b].append((a,c))
T = list(map(int,input().split()))
inf = 1000
dist = [[10 ** 6] * (inf + 1) for _ in range(N)]
dist[0][T[0]] = 0
q = [(0,0,0)]
import heapq
while q:
    d,now,time = heapq.heappop(q)
    #print(d,now,time)
    if dist[now][time] < d:contnue
    if now == N - 1:break
    time += T[now]
    d += T[now]
    if time > inf:
        time = inf
    for v,c in G[now]:
        tmp = d + c // time
        if dist[v][time] > tmp:
            dist[v][time] = tmp
            heapq.heappush(q,(tmp,v,time))
ans = 10 ** 6
for time in range(inf + 1):
    if ans > dist[-1][time]:
        ans = dist[-1][time]
print(ans)