#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r) - 1;i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n; cin >> n;
	vector<long long>a(n), b(n), c(n);
	rep(i, n)cin >> a[i];
	rep(i, n)cin >> b[i];
	rep(i, n)cin >> c[i];
	long long ans = 0;
	rep(t, 2) {
		vector dp(n + 1, vector<long long>(5, -LINF));
		dp[0][0] = 0;
		rep(i, n) {
			rep(j, 5)rep2(k, j, 5) {
				long long val = 0;
				if (0 == k || 4 == k)val = a[i];
				else if (1 == k || 3 == k)val = b[i];
				else val = c[i];
				chmax(dp[i + 1][k], dp[i][j] + val);
			}
		}
		rep(i, 5)chmax(ans, dp[n][i]);
		rep(i, n)c[i] = a[i];
	}
	cout << ans << endl;
	return 0;
}