# 2次元dpでよいか
# dp[i個目][帽子が赤0、青1]のときの最高得点

N = int(input())
A = [0]+list(map(int, input().split()))
B = [0]+list(map(int, input().split()))
X = [0]+list(map(int, input().split()))
Y = [0]+list(map(int, input().split()))

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

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

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