#include <iostream>

using namespace std;

#define maxN 100005


int rsp, A[maxN], sol[maxN];

int main()
{
	freopen ("oo.in", "r", stdin);
	freopen ("oo.out", "w", stdout);
	
	int N;
	
	scanf ("%d", &N);
	
	for (int i = 1; i <= N; ++ i) scanf ("%d", &A[i]);
	
	for (int i = 3; i <= N; ++ i)
	{
		sol[i] = sol[i - 3] + A[i] + A[i - 1];
		
		rsp = max (rsp, sol[i]);
	}
	
	sol[1] = sol[N - 2] + A[1] + A[N];	
	sol[2] = sol[N - 1] + A[1] + A[2];
	
	rsp = max (rsp, sol[1]);
	rsp = max (rsp, sol[2]);
	
	printf ("%d", rsp);
	
	return 0;
}