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) for i in range(N + 1)]
dp[0][0] = 0

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

print(dp[-1][-1])