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

void fast_io() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
}

int main() {
	fast_io();
	int n;
	cin >> n;
	vector<long long> a(n), b(n), c(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	for (int i = 0; i < n; i++) {
		cin >> b[i];
	}
	for (int i = 0; i < n; i++) {
		cin >> c[i];
	}
	vector<vector<long long>> dp(n + 1, vector<long long>(6, -1e18));
	dp[0][0] = 0;
	for (int i = 0; i < n; i++) {
		// 0 -> 0, 1, 2
		dp[i + 1][0] = max(dp[i + 1][0], dp[i][0] + a[i]);
		dp[i + 1][1] = max(dp[i + 1][1], dp[i][0] + b[i]);
		dp[i + 1][2] = max(dp[i + 1][2], dp[i][0] + c[i]);
		// 1 -> 2, 5
		dp[i + 1][1] = max(dp[i + 1][1], dp[i][1] + b[i]);
		dp[i + 1][2] = max(dp[i + 1][2], dp[i][1] + c[i]);
		dp[i + 1][5] = max(dp[i + 1][5], dp[i][1] + a[i]);
		// 2 -> 2, 3
		dp[i + 1][2] = max(dp[i + 1][2], dp[i][2] + c[i]);
		dp[i + 1][3] = max(dp[i + 1][3], dp[i][2] + b[i]);
		// 3 -> 3, 4
		dp[i + 1][3] = max(dp[i + 1][3], dp[i][3] + b[i]);
		dp[i + 1][4] = max(dp[i + 1][4], dp[i][3] + a[i]);
		// 4 -> 4
		dp[i + 1][4] = max(dp[i + 1][4], dp[i][4] + a[i]);
		// 5 -> 5, 3
		dp[i + 1][5] = max(dp[i + 1][5], dp[i][5] + a[i]);
		dp[i + 1][3] = max(dp[i + 1][3], dp[i][5] + b[i]);
	}
	cout << *max_element(dp[n].begin(), dp[n].end()) << endl;
}