N,H=map(int,input().split())
A=list(map(int,input().split()))
B=list(map(int,input().split()))

S=[0 for _ in range(N+1)]
for i in range(N):S[i+1]=S[i]+B[i]

r=0
len=1
a=A[0]
b=B[0]
ans=0
for l in range(N):
    while r+1<N and b+B[r+1]*(len+1)<=H:
        r+=1
        len+=1
        a+=A[r]
        b+=B[r]*len
    if b<=H:ans=max(ans,a)
    a-=A[l]
    b-=S[r+1]-S[l]
    len-=1
print(ans)