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

inf = 1 << 60

dp0, dp1, dp22, dp20, dp3, dp4 = 0, -inf, -inf, -inf, -inf, -inf

for a, b, c in zip(A, B, C):
    dp0nxt = dp0 + a
    dp1nxt = max(dp0, dp1) + b

    dp22nxt = max([dp22, dp1, dp0]) + c
    dp20nxt = max(dp20, dp1) + a

    dp3nxt = max([dp3, dp22, dp20]) + b
    dp4nxt = max([dp4, dp3, dp22]) + a

    dp0, dp1, dp22, dp20, dp3, dp4 = dp0nxt, dp1nxt, dp22nxt, dp20nxt, dp3nxt, dp4nxt

print(max([dp0, dp1, dp22, dp20, dp3, dp4]))