#include <bits/stdc++.h>
using namespace std;
//*/
#include <atcoder/all>
using namespace atcoder;
// //*/
// #pragma GCC optimize("Ofast,unroll-loops,no-stack-protector,fast-math")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
// #pragma GCC target("avx,avx2,fma")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
#define rep(i,n) for(int i=0;i<n;i++)
#define Rep(i,a,b) for(int i=a;i<b;i++)
#define ALL(x) (x).begin(),(x).end()
#define dbgv(x); for(auto now : x) cout << now << " "; cout << endl;
//using P = pair<int,int>;
using ll = long long;
using ull = unsigned long long;
//*/
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<int> vint;
random_device rnd;
mt19937 rng(rnd());

ll dp[3][2][2][200010];
ll dp2[2][3][200010];
void solve(){
    int n; cin >> n;
    vll a(n),b(n),c(n);
    rep(i,n) cin >> a[i];
    rep(i,n) cin >> b[i];
    rep(i,n) cin >> c[i];
    dp[0][0][0][0] = a[0];
    dp[1][1][0][0] = b[0];
    dp[2][1][1][0] = c[0];
    rep(i,n)if(i){
        dp[0][0][0][i] = max({dp[0][0][0][i-1]})+a[i];
        dp[0][1][0][i] = max({dp[0][1][0][i-1],dp[1][1][0][i-1]})+a[i];
        dp[0][1][1][i] = max({dp[0][1][1][i-1],dp[1][1][1][i-1],dp[2][1][1][i-1]})+a[i];
        dp[1][1][0][i] = max({dp[0][0][0][i-1],dp[1][1][0][i-1]})+b[i];
        dp[1][1][1][i] = max({dp[1][1][1][i-1],dp[2][1][1][i-1]})+b[i];
        dp[2][1][1][i] = max({dp[1][1][0][i-1],dp[2][1][1][i-1]})+c[i];
    }
    ll ans = 0;
    rep(i,3)rep(j,2)rep(k,2) chmax(ans,dp[i][j][k][n-1]);

    dp2[0][0][0] = a[0];
    dp2[1][1][0] = b[0];

    rep(i,n)if(i){
        dp2[0][0][i] = max({dp2[0][0][i-1]})+a[i];
        dp2[0][1][i] = max({dp2[0][1][i-1],dp2[1][1][i-1]}) + a[i];
        dp2[0][2][i] = max({dp2[0][2][i-1],dp2[1][2][i-1]}) + a[i];
        dp2[1][1][i] = max({dp2[0][0][i-1],dp2[1][1][i-1]}) + b[i];
        dp2[1][2][i] = max({dp2[0][1][i-1],dp2[1][2][i-1]}) + b[i];
    }
    rep(i,2)rep(j,3) chmax(ans,dp2[i][j][n-1]);
    cout << ans << endl;
}

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int t = 1; //cin >> t;
  rep(testcase,t) solve();
}