n,h=map(int,input().split())
a=list(map(int,input().split()))
b=list(map(int,input().split()))
ans=0
r=0
now=0
now2=0
now3=0
cnt=0
for i in range(n):
  if i==r:
    r+=1
    now+=a[i]
    now2+=b[i]
    now3+=b[i]
    cnt=1
  for j in range(r,n):
    if now2+(cnt+1)*b[j]<=h:
      now+=a[j]
      now2+=(cnt+1)*b[j]
      now3+=b[j]
      cnt+=1
      r+=1
    else:
      break
  if now2<=h:
    ans=max(now,ans)
  now-=a[i]
  now2-=now3
  now3-=b[i]
  cnt-=1
  
print(ans)