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

dp = [[0,0,0,0,0,0] for i in range(N + 1)]
for i in range(N):
  a,b,c = A[i],B[i],C[i]
  dp[i + 1][0] = dp[i][0] + a
  dp[i + 1][1] = max(dp[i][0],dp[i][1]) + b
  dp[i + 1][2] = max(dp[i][0],dp[i][1],dp[1][2]) + a
  dp[i + 1][3] = max(dp[i][0],dp[i][1],dp[i][3]) + c
  dp[i + 1][4] = max(dp[i][2],dp[i][3],dp[i][4]) + b
  dp[i + 1][5] = max(dp[i]) + a
print(max(dp[N]))