import io
import sys
from collections import defaultdict, deque, Counter
from itertools import permutations, combinations, accumulate
from heapq import heappush, heappop
from bisect import bisect_right, bisect_left
from math import gcd
import math

_INPUT = """\
6
7 22
5 10 15 20 25 30 35
10 5 4 3 2 5 10
7 1
5 10 15 20 25 30 35
10 5 4 3 2 5 10
7 1000000000
5 10 15 20 25 30 35
10 5 4 3 2 5 10
10 23
3 1 4 1 5 9 2 6 5 3
2 7 1 8 2 8 1 8 2 8
"""

def input():
  return sys.stdin.readline()[:-1]

def solve(test):
  N,H=map(int, input().split())
  A=list(map(int, input().split()))
  B=list(map(int, input().split()))
  b=[0]+list(accumulate(B))
  now=0
  ans=0
  h=0
  a=0
  for i in range(N):
    while now<N and h+(now-i+1)*B[now]<=H:
      h+=(now-i+1)*B[now]
      a+=A[now]
      now+=1
      ans=max(ans,a)
    h-=b[now]-b[i]
    a-=A[i]
  print(ans)

def random_input():
  from random import randint,shuffle
  N=randint(1,10)
  M=randint(1,N)
  A=list(range(1,M+1))+[randint(1,M) for _ in range(N-M)]
  shuffle(A)
  return (" ".join(map(str, [N,M]))+"\n"+" ".join(map(str, A))+"\n")*3

def simple_solve():
  return []

def main(test):
  if test==0:
    solve(0)
  elif test==1:
    sys.stdin = io.StringIO(_INPUT)
    case_no=int(input())
    for _ in range(case_no):
      solve(0)
  else:
    for i in range(1000):
      sys.stdin = io.StringIO(random_input())
      x=solve(1)
      y=simple_solve()
      if x!=y:
        print(i,x,y)
        print(*[line for line in sys.stdin],sep='')
        break

#0:提出用、1:与えられたテスト用、2:ストレステスト用
main(0)