#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

void solve() {
  ll n;
  cin >> n;
  vector<ll> a(n);
  rep(i, n) cin >> a[i];
  vector<ll> b(n);
  rep(i, n) cin >> b[i];
  vector<ll> c(n);
  rep(i, n) cin >> c[i];
  vector dp(3, vector<ll>(3, 0));
  rep(i, n) {
    vector nex(3, vector<ll>(3, -1));
    rep(nj, 3) rep(nk, 3) rep(pj, nj + 1) rep(pk, nk + 1) nex[nj][nk] =
        max(nex[nj][nk], dp[pj][pk]);
    rep(j, 3) rep(k, 3) {
      ll cnt = (j == 1) + (k == 1);
      if (cnt == 0)
        nex[j][k] += a[i];
      if (cnt == 1)
        nex[j][k] += b[i];
      if (cnt == 2)
        nex[j][k] += c[i];
    }
    swap(dp, nex);
  }
  ll ans = 0;
  rep(j, 3) rep(k, 3) ans = max(ans, dp[j][k]);
  cout << ans << '\n';
}

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);
  int T = 1;
  for (int t = 0; t < T; t++) {
    solve();
  }
  return 0;
}