n, h = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
s = [0]
for i in range(n):
    s.append(s[i] + B[i])
ans = 0
a = 0
b = 0
r = 0
for l in range(n):
    while r < n and b + (r - l + 1) * B[r] <= h:
        b += (r - l + 1) * B[r]
        a += A[r]
        r += 1
    if b <= h:
        ans = max(ans, a)
    if l == r:
        r += 1
    else:
        b -= s[r] - s[l]
        a -= A[l]
print(ans)