#include <bits/stdc++.h>
using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    vector<long long> A(N),B = A,C = A;
    for(auto &a : A) cin >> a;
    for(auto &a : B) cin >> a;
    for(auto &a : C) cin >> a;

    long long inf = 1e18;
    vector<vector<long long>> dp(3,vector<long long>(3,-inf));
    dp.at(0).at(0) = 0;
    auto chmax = [&](auto &a,auto b) -> void {a = max(a,b);};
    for(int i=0; i<N; i++){
        long long a = A.at(i),b = B.at(i),c = C.at(i);
        vector<vector<long long>> next(3,vector<long long>(3,-inf));
        for(int i=0; i<3; i++){
            for(int k=0; k<3; k++){
                if(dp.at(i).at(k) == inf) continue;
                if(i == 0){
                    chmax(next.at(i).at(k),dp.at(i).at(k)+a);
                    if(k < 2) chmax(next.at(i+1).at(k+1),dp.at(i).at(k)+b);
                }
                else if(i == 1){
                    chmax(next.at(i).at(k),dp.at(i).at(k)+b);
                    chmax(next.at(0).at(k),dp.at(i).at(k)+a);
                    if(k < 2) chmax(next.at(i+1).at(k+1),dp.at(i).at(k)+c);
                }
                else{
                    chmax(next.at(i).at(k),dp.at(i).at(k)+c);
                    chmax(next.at(1).at(k),dp.at(i).at(k)+b);
                    chmax(next.at(0).at(k),dp.at(i).at(k)+a);
                }
            }
        }
        swap(dp,next);
    }
    long long answer = 0;
    for(auto &h : dp) for(auto &w : h) answer = max(answer,w);
    cout << answer << endl;
}