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

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<ll, 5> dp{}, dp2{};
    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] + b[i], dp[2]);
        dp[4] = max(dp[4] + a[i], dp[3]);
        dp2[0] += a[i];
        dp2[1] = max(dp2[1] + b[i], dp2[0]);
        dp2[2] = max(dp2[2] + c[i], dp2[1]);
        dp2[3] = max(dp2[3] + b[i], dp2[2]);
        dp2[4] = max(dp2[4] + a[i], dp2[3]);
    }
    cout << max(*max_element(dp.begin(), dp.end()), *max_element(dp2.begin(), dp2.end())) << '\n';
}