#include<fstream.h>
int main()
{int max,lim1,lim2,sum,smax,s,n,v[100001],i;
ifstream q("oo.in");
ofstream w("oo.out");
q>>n;
for(i=1;i<=n;i++)
	 q>>v[i];
int pos=1;
s=0;
while(pos==1)
{smax=0;
for(i=1;i<=n;i++)
	{lim1=i-1;
	lim2=i;
	if(i==1)
	 lim1=n;
	sum=v[lim1]+v[lim2];
	if(sum>smax)
	 smax=sum;}
for(i=1;i<=n;i++)
	{lim1=i-1;
	lim2=i;
	if(i==1)
	 lim1=n;
	if(lim1>-1&&lim2>-11)
	if(v[lim1]+v[lim2]==smax)
	 {s=s+v[lim1]+v[lim2];
	 v[lim1]=-1;
	 v[lim2]=-1;
	 if(lim1>1)
		v[lim1-1]=-1;
	 else
		v[n]=-1;
	 v[lim2+1]=-1;}}
	pos=0;
	for(i=1;i<=n;i++)
	{lim1=i-1;
	lim2=i;
	if(i==1)
	 lim1=n;
	if(v[lim1]!=-1&&v[lim2]!=-1)
	 pos=1;} }
w<<s;
return 0;}