n,c=map(int,input().split())
a=list(map(int,input().split()))
ok=0
ng=10**10
while ng-ok>1:
  m=(ok+ng)//2
  b=a.copy()
  for i in reversed(range(1,n)):
    t=max(m*c-b[i],0)
    b[i]+=t
    b[i-1]-=t
  if b[0]>=m*c:
    ok=m
  else:
    ng=m
print(ok)