import heapq

INF=10**18
N,M=map(int,input().split())

G=[[]for i in range(N)]
for i in range(M):
    A,B,C=map(int,input().split())
    G[A-1]+=[(B-1,C)]
    G[B-1]+=[(A-1,C)]
T=list(map(int,input().split()))

dist=[[INF]*1002 for i in range(N)]
dist[0][0]=0

PQ=[(0,0,0)]
while PQ:
    c,v,p=heapq.heappop(PQ)
    if dist[v][p]<c:
        continue
    c+=T[v]
    p=min(p+T[v],1001)
    for e in G[v]:
        if dist[e[0]][p]>c+e[1]//p:
            dist[e[0]][p]=c+e[1]//p
            heapq.heappush(PQ,(c+e[1]//p,e[0],p))
print(min(dist[N-1]))