N=int(input())
A=list(map(int,input().split()))
B=list(map(int,input().split()))
C=list(map(int,input().split()))
ans=0
dp=[0]*5
for i in range(N):
    dp[0]+=A[i]
    dp[1]+=B[i]
    dp[2]+=A[i]
    dp[3]+=B[i]
    dp[4]+=A[i]
    for t in range(1,5):
        dp[t]=max(dp[t],dp[t-1])
ans=max(ans,dp[4])
dp=[0]*5
for i in range(N):
    dp[0]+=A[i]
    dp[1]+=B[i]
    dp[2]+=C[i]
    dp[3]+=B[i]
    dp[4]+=A[i]
    for t in range(1,5):
        dp[t]=max(dp[t],dp[t-1])
ans=max(ans,dp[4])
print(ans)