import sys
input = sys.stdin.readline

N,K=map(int,input().split())
A=list(map(int,input().split()))
C=list(map(int,input().split()))

DP=[[[10**9,-1] for i in range(N)] for j in range(N)]

for i in range(N):
    DP[i][0]=[C[i],C[i]]

for j in range(1,N):
    for i in range(N):
        # DP[i][j]
        # [i,i+j]

        for k in range(j):
            # [i,i+k], [i+k+1,j]
            # DP[i][k], DP[i+k+1][j-k]

            a,b=DP[i][k]
            c,d=DP[(i+k+1)%N][j-k-1]

            #print(j,i,k,a,b,c,d)

            if a==10**9 or c==10**9:
                continue

            if (b<c and c-b>K) or (d<a and a-d>K):
                continue
            else:
                DP[i][j][0]=min(DP[i][j][0],a,c)
                DP[i][j][1]=max(DP[i][j][1],b,d)

            

            
    
S=[0]
for a in A+A:
    S.append(S[-1]+a)

ANS=0
for i in range(N):
    for j in range(N):
        if DP[i][j][1]!=-1:
            ANS=max(ANS,S[i+j+1]-S[i])

print(ANS)