import sys
input = sys.stdin.readline

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()))
dp = [[0]*2 for _ in range(2*N+1)]

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

print(max(dp[2*N]))