#include <iostream>
#include <fstream>

using namespace std;
ifstream fin("oo.in");
ofstream fout("oo.out");

int n, i, j, l, mx, nr, op[200005], v[200005], rez;

int main () {
    
    fin >> n;
	for (i = 1; i <= n; i++)
    {
        fin >> v[i];
		v[i+n] = v[i];
    }
	
	for (j = 5; j <= 10; j++)
	{
		for (i = j+2; i <= n+j-1; i++)
		{
			op[i] = v[i]+v[i-1] + max(op[i-3], max(op[i-4], op[i-5]));;
			if (op[i] > rez)	rez = op[i];
			op[i-5] = 0;
		}
		
		for (i = n+j-6; i <= n+j-1; i++)
			op[i] = 0;
	}
	
	fout << rez << "\n";
}