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

template<class T> istream& operator >> (istream& is, vector<T>& vec) {
    for(T& x : vec) is >> x;
    return is;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<int> a(n), b(n), c(n);
    cin >> a >> b >> c;
    array<long long, 6> dp{};
    for(int i = 0; i < n; i++){
        dp[0] += a[i];
        dp[1] = max(dp[1] + b[i], dp[0]);
        dp[2] = max(dp[2] + a[i], dp[1]);
        dp[3] = max(dp[3] + c[i], dp[1]);
        dp[4] = max(dp[4] + b[i], max(dp[2], dp[3]));
        dp[5] = max(dp[5] + a[i], dp[4]);
    }
    cout << *max_element(dp.begin(), dp.end()) << '\n';
}