from collections import deque
N,H = map(int,input().split())
A = list(map(int,input().split()))
B = list(map(int,input().split()))

rui = []
for i,v in enumerate(B):
    if i == 0:
        rui.append(v)
    else:
        rui.append(rui[-1]+v)

#print("rui")
#print(rui)
#print("B")
#print(B)
#print("A")
#print(A)
#print()

Q1,Q2 = deque(list(range(N))),deque()

tired = 0
manzoku = 0
ans = 0

for i,v in enumerate(B):
    while Q1:
        if (len(Q2)+1)*B[Q1[0]] + tired <= H:
            tired += (len(Q2)+1)*B[Q1[0]]
            manzoku += A[Q1[0]]
            Q2.append(Q1.popleft())
        else:
            break

    ans = max(ans,manzoku)

#    print("before","Q2",Q2,"tired",tired,"manzoku",manzoku)

    if len(Q2):
        nex1 = Q2[0]
        nex2 = Q2[-1]
        tired -= rui[nex2]
        if nex1 != 0:
            tired += rui[nex1-1]
        manzoku -= A[nex1]
        Q2.popleft()
    else:
        Q1.popleft()

#    print("after","Q2",Q2,"tired",tired,"manzoku",manzoku)
#    print()
print(ans)