#include<fstream>
using namespace std;
ifstream f("oo.in");
ofstream g("oo.out");
int i,k,k1,maxi,n,v[100001],s1[100001],s2[100001],s3[100001];
int main()
{f>>n;
for(i=1;i<=n;++i)
	f>>v[i];
for(i=1;i<=n-2;++i)
{k=i-3;
k1=i-1;
if(k<1)
	k+=n;
if(k1<1)
	k1+=n;
s1[i]=max(s1[k]+v[k1]+v[i],s1[i-1]);
}
for(i=2;i<=n-1;++i)
{k=i-3;
k1=i-1;
if(k<1)
	k+=n;
if(k1<1)
	k1+=n;
s2[i]=max(s2[k]+v[k1]+v[i],s2[i-1]);
}
for(i=3;i<=n;++i)
{k=i-3;
k1=i-1;
if(k<1)
	k+=n;
if(k1<1)
	k1+=n;
s3[i]=max(s3[k]+v[k1]+v[i],s3[i-1]);
}
maxi=s1[n-2];
if(maxi<s2[n-1])
	maxi=s2[n-1];
if(maxi<s3[n])
	maxi=s3[n];
g<<maxi<<'\n';
return 0;
}