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


def calc(m) -> int:
    a = 0
    b = 0
    s = 0
    for i in range(m):
        s += B[i] * (i+1)
        a += A[i]
        b += B[i]

    res = 0
    if s <= H:
        res = a
    for i in range(m, N):
        s -= b
        a -= A[i-m]
        b -= B[i-m]
        s += B[i] * m
        a += A[i]
        b += B[i]
        if s <= H:
            res = max(res, a)
    return res


ans = 0
lo = 1
hi = N
while lo <= hi:
    m = (lo + hi) // 2
    res = calc(m)
    #print(f'{res=} {m=}')
    if res > 0:
        ans = max(ans, res)
        lo = m + 1
    else:
        hi = m - 1

print(ans)