def max_satisfaction(N, H, A, B):
    max_satisfaction = 0
    current_fatigue = 0
    current_satisfaction = 0
    left = 0
    
    for right in range(N):
        current_satisfaction += A[right]
        current_fatigue += B[right] * (right - left + 1)
        
        while current_fatigue > H:
            current_fatigue -= B[left] * (right - left + 1)
            left += 1
            current_satisfaction -= A[left - 1]
            
        max_satisfaction = max(max_satisfaction, current_satisfaction)
        
    return max_satisfaction

# Input reading
import sys
input = sys.stdin.read
data = input().split()

N = int(data[0])
H = int(data[1])
A = list(map(int, data[2:N+2]))
B = list(map(int, data[N+2:2*N+2]))

result = max_satisfaction(N, H, A, B)
print(result)