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

# Prepare cumulative sum of B
S = [0] * (N + 1)  
for i in range(N):
  S[i + 1] = S[i] + B[i]

# Solve using sliding window method
ans = 0
tmp = 0
need_hp = 0
r = 0

for l in range(N):
    while r < N and need_hp + B[r] * (r - l + 1) <= H:
      tmp += A[r]
      need_hp += B[r] * (r - l + 1)
      r += 1

    # Debugging output (optional)
    # print(l, r, need_hp, tmp)
    
    # Changing Maximum
    ans = max(ans, tmp)

    # Preparing for incrementing l
    if l == r:
      r += 1
    else:
      tmp -= A[l]
      need_hp -= S[r] - S[l]  # Cumulative sum for O(1) update

# Output
print(ans)