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

INF = 10**18
dp = [[-INF]*6 for _ in range(N+1)]
dp[0][0] = 0
for i in range(N):
    for j in range(6):
        if dp[i][j] != -INF:
            if j == 0:
                dp[i+1][0] = max(dp[i+1][0], dp[i][0]+A[i])
                dp[i+1][1] = max(dp[i+1][1], dp[i][0]+B[i])
                dp[i+1][2] = max(dp[i+1][2], dp[i][0]+C[i])
            elif j == 1:
                dp[i+1][1] = max(dp[i+1][1], dp[i][1]+B[i])
                dp[i+1][2] = max(dp[i+1][2], dp[i][1]+C[i])
                dp[i+1][5] = max(dp[i+1][5], dp[i][1]+A[i])
            elif j == 2:
                dp[i+1][2] = max(dp[i+1][2], dp[i][2]+C[i])
                dp[i+1][3] = max(dp[i+1][3], dp[i][2]+B[i])
                dp[i+1][4] = max(dp[i+1][4], dp[i][2]+A[i])
            elif j == 3:
                dp[i+1][3] = max(dp[i+1][3], dp[i][3]+B[i])
                dp[i+1][4] = max(dp[i+1][4], dp[i][3]+A[i])
            elif j == 5:
                dp[i+1][5] = max(dp[i+1][5], dp[i][5]+A[i])
                dp[i+1][3] = max(dp[i+1][3], dp[i][5]+B[i])
            else:
                dp[i+1][4] = max(dp[i+1][4], dp[i][4]+A[i])

print(max(dp[-1]))