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()))

pre = [A[0], B[0]]
for i in range(2 * N - 1):
    dp = [0] * 2
    if i % 2 == 0:
        dp[0] = max(pre[0] + A[i + 1] + X[i//2], pre[1] + A[i + 1] + Y[i//2])
        dp[1] = max(pre[0] + B[i + 1] + Y[i//2], pre[1] + B[i + 1] + X[i//2])
    else:
        dp[0] = max(pre[0] + A[i + 1] , pre[1] + A[i + 1] )
        dp[1] = max(pre[0] + B[i + 1] , pre[1] + B[i + 1] )
    dp, pre = pre, dp
print(max(pre))