n,m=map(int,input().split())
e=[[] for i in range(n)]
for i in range(m):
  a,b,c=map(int,input().split())
  a-=1
  b-=1
  e[a]+=[(b,c)]
  e[b]+=[(a,c)]
o=list(map(int,input().split()))
X=10**10
v=[[(X,X)]*1002 for i in range(n)]
v[0][1]=(0,0)
q=[(v[0][1],0,1)]
from heapq import heappush,heappop
while len(q)>0:
  sc,sp,so=heappop(q)
  if sc>v[sp][so]:
    continue
  if sp==n-1:
    break
  st1,st2=sc[0],-sc[1]
  tt2=st2+o[sp]
  to=so+1
  for tp,tc in e[sp]:
    tt1=st1+o[sp]+tc//tt2
    if to<=1001 and v[tp][to]>(tt1,-tt2):
      v[tp][to]=(tt1,-tt2)
      heappush(q,(v[tp][to],tp,to))
print(min(v[n-1][i][0] for i in range(1002)))