#include<fstream>
using namespace std;
int n,i,j,a[100],b[100],x[100],aux,ok,nr,maxim,p,s;
int main()
{
ifstream f("oo.in");
ofstream g("oo.out");
f>>n;
for(i=1;i<=n;i++)
   f>>a[i];
for(i=1;i<n;i++)
    b[i]=a[i]+a[i+1];
b[n]=a[1]+a[n];
for(i=1;i<=n;i++)
    x[i]=b[i];
ok=0;
while(ok==0)
{
maxim=-10;
for(i=1;i<=n;i++)
    if(b[i]>maxim)
        {
        maxim=b[i];
        p=i;
        }
s=s+maxim;
if(p<n-2 && p>2)
    b[p-2]=b[p-1]=b[p]=b[p+1]=b[p+2]=0;
if(p==1)
    b[1]=b[2]=b[3]=b[n]=b[n-1]=0;
if(p==2)
    b[1]=b[2]=b[3]=b[4]=b[n]=0;
if(p==n)
    b[n]=b[n-1]=b[n-2]=b[1]=b[2]=0;
if(p==n-1)
    b[n]=b[n-1]=b[n-2]=b[n-3]=b[1]=0;
nr=0;                                                                                                                                                                                                                                                                          
for(i=1;i<=n;i++)
    if(b[i]!=0)
        nr++;
if(nr==0)
    ok=1;
}
g<<s;
f.close();
g.close();
return 0;    
}