import collections,sys,math,functools,operator,itertools,bisect,heapq,decimal,string,time,random
#sys.setrecursionlimit(10**9)
#sys.set_int_max_str_digits(0)
input = sys.stdin.readline
#n = int(input())
#alist = list(map(int,input().split()))
#alist = []
#s = input()
n,h = map(int,input().split())
a = list(map(int,input().split()))
b = list(map(int,input().split()))
ans = 0
#https://github.com/tsutaj/pastbook-2-source-code/blob/main/python/chapter3/3-2-1.py
l, r = 0, 0
fat = 0
temp = 0
res = 0
for l in range(n):
    while r < n and fat + b[r] * (r-l+1) <= h:
        fat += b[r] * (r-l+1)
        temp += b[r]
        res += a[r]
        r += 1
    ans = max(ans, res)
    if r - l >= 1:
        fat -= temp
        temp -= b[l]
        res -= a[l]
    else:
        r += 1
print(ans)