N = int(input())
A = [list(map(int, input().split())) for _ in range(3)]
dp = [0] * 6
dp[0] = 0
for i in range(N):
    dp2 = [0] * 6
    dp2[0] = dp[0] + A[0][i]
    dp2[1] = max(dp[0], dp[1]) + A[1][i]
    dp2[2] = max(dp[1], dp[2]) + A[0][i]
    dp2[3] = max(dp[2], dp[3], dp[5]) + A[1][i]
    dp2[4] = max(dp[3], dp[4], dp[5]) + A[0][i]
    dp2[5] = max(dp[0], dp[1], dp[5]) + A[2][i]
    dp = dp2
print(max(dp))