n = int(input())
a = list(map(int,input().split()))
b = list(map(int,input().split()))
x = list(map(int,input().split()))
y = list(map(int,input().split()))

dp = [[0,0] for i in range(2*n)]
dp[0] = [a[0],b[0]]
for i in range(1, 2*n):
  ai,bi = a[i], b[i]
  if i % 2 == 1:
    xi,yi = x[i//2], y[i//2]
    dp[i][0] = max(dp[i-1][0] + ai + xi, dp[i-1][1] + ai + yi)
    dp[i][1] = max(dp[i-1][0] + bi + yi, dp[i-1][1] + bi + xi)
  else:
    dp[i][0] = max(dp[i-1]) + ai
    dp[i][1] = max(dp[i-1]) + bi
  
print(max(dp[-1]))