#include <fstream>

using namespace std;
ifstream cin ("oo.in");
ofstream cout ("oo.out");
int d[100003],v[100013],n;
int dp (int st, int dr)
{
    d[st]=d[st-1]=0;
    d[st+1]=v[st+1]+v[st];
    for(int i=st+2;i<=dr;++i)
        d[i]=max(d[i-1],v[i]+v[i-1]+d[i-3]);
    return d[dr];
}
int main()
{
    int i,j;
    cin>>n;
    for(i=1;i<=n;++i)
        cin>>v[i];
    v[n+1]=v[1];
    v[n+2]=v[2];
    cout<<max(max(dp(2,n),dp(3,n+1)),dp(1,n-1));
    return 0;
}