N,H=map(int,input().split())
A=list(map(int,input().split()))
B=list(map(int,input().split()))
v1=[0]*N
v2=[0]*N
va=[0]*N
for i in range(N):
  v1[i]=v1[i-1]+B[i]
  v2[i]=v2[i-1]+(i+1)*B[i]
  va[i]=va[i-1]+A[i]
result=0
for i in range(N):
  if B[i]>H:
    continue
  l=i
  r=N-1
  while True:
    if l==r:
      break
    m=(l+r+1)//2
    w=v2[m]
    if i>0:
      w-=v2[i-1]
      w-=(v1[m]-v1[i-1])*i
    if w<=H:
      l=m
    else:
      r=m-1
  score=va[r]
  if i>0:
    score-=va[i-1]
  result=max(result,score)
print(result)