#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  VI a(n), b(n), c(n);
  rep(i, n) cin >> a[i];
  rep(i, n) cin >> b[i];
  rep(i, n) cin >> c[i];
  constexpr long long INF = 1002003004005006007;
  ll dp[6]{};
  rep(i, n) {
    ll ndp[6]{};
    chmax(ndp[0], dp[0] + a[i]);
    chmax(ndp[1], dp[0] + b[i]);
    chmax(ndp[2], dp[0] + c[i]);
    chmax(ndp[3], dp[1] + a[i]);
    chmax(ndp[1], dp[1] + b[i]);
    chmax(ndp[2], dp[1] + c[i]);
    chmax(ndp[5], dp[2] + a[i]);
    chmax(ndp[4], dp[2] + b[i]);
    chmax(ndp[2], dp[2] + c[i]);
    chmax(ndp[3], dp[3] + a[i]);
    chmax(ndp[4], dp[3] + b[i]);
    chmax(ndp[5], dp[4] + a[i]);
    chmax(ndp[4], dp[4] + b[i]);
    chmax(ndp[5], dp[5] + a[i]);
    swap(dp, ndp);
  }
  cout << *max_element(all(dp)) << '\n';
}