INT = lambda : int(input())
MI = lambda : map(int, input().split())
MI_DEC = lambda : map(lambda x : int(x)-1, input().split())
LI = lambda : list(map(int, input().split()))
LI_DEC = lambda : list(map(lambda x : int(x)-1, input().split()))
INF = float('inf')
CEIL = lambda a, b : (a + b - 1) // b

N, H = MI()
A = LI()
B = LI()

Bsums = [0]
for i in range(N):
     Bsums.append(Bsums[i] + B[i])


ans, a, h, d = 0, 0, 0, 1
right = 0
for left in range(N):
    while right < N and h + B[right] * d <= H:
         a += A[right]
         h += B[right] * d
         d += 1
         right += 1

    ans = max(ans, a)

    if left == right:
         right += 1

    else:
         d -= 1
         a -= A[left]
         h -= (Bsums[right] - Bsums[left])


print(ans)