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

for i in range(n):
    B[i] -= A[i]
    C[i] -= A[i]

ans = sum(A)

dp = [0] * 5
for i in range(n):
    ndp = [0] * 5
    ndp[0] = dp[0]
    ndp[1] = max(dp[0], dp[1]) + B[i]
    ndp[2] = max(dp[1], dp[2]) + C[i]
    ndp[3] = max(dp[2], dp[3]) + B[i]
    ndp[4] = max(dp[3], dp[4])
    dp = ndp

add = max(dp)

dp = [0] * 5
for i in range(n):
    ndp = [0] * 5
    ndp[0] = dp[0]
    ndp[1] = max(dp[0], dp[1]) + B[i]
    ndp[2] = max(dp[1], dp[2])
    ndp[3] = max(dp[2], dp[3]) + B[i]
    ndp[4] = max(dp[3], dp[4])
    dp = ndp

add = max(add, *dp)

print(ans + add)