from collections import deque  
mod=998244353
from sys import stdin, setrecursionlimit
input = stdin.readline
readline = stdin.readline
import math
N,H=map(int, stdin.readline().split())
A=list(map(int, input().split()))
B=list(map(int, input().split()))
AA=[0]
for a in A:
  AA.append(AA[-1]+a)
BB=[0]
for b in B:
  BB.append(BB[-1]+b)
# print(AA)
# print(BB)

if min(B)>H:
  print(0)
  exit()

ans=0;c=0;r=-1
for l in range(N):
  while r+1<N and c+(r+1-l+1)*B[r+1]<=H:
    c+=(r+1-l+1)*B[r+1]
    r+=1 
  ans=max(ans,AA[r+1]-AA[l])
  c-=BB[r+1]-BB[l]
print(ans)