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

dp = [-1] * (K + 1)
dp[0] = 0

for i in range(1, N + 1):
  ndp = [-1] * (K + 1)
  ndp[0] = dp[0] + A[i - 1] + C[i - 1]
  for j in range(K):
    ndp[j + 1] = max(dp[j] + A[i - 1] + B[i - 1], dp[j + 1] + A[i - 1] + C[i - 1])
  dp = ndp
print(dp[-1])