#include<stdio.h>
int n,i,s[100],v[1000],smax1,smax2,j,poz;
FILE *in=fopen("oo.in","rt"),*out=fopen("oo.out","wt");
int main()
{
	fscanf(in,"%d",&n);
	for(i=1;i<=n;i++)
	{
		fscanf(in,"%d",&v[i]);
		if(i>1&&i<=n)
			s[i]=v[i]+v[i-1];
		if(i==n)
			s[1]=v[i]+v[1];
			
	}
	for(j=1;j<=n;j++)
	{
		for(i=1;i<n;i++)
			if(smax1<s[i]&&s[i]!=-1&&s[i-1]!=-1&&s[i+1]!=-1)
			 {
				smax1=s[i];
				poz=i;
			 }
		smax2+=smax1;
		s[poz]=-1;
		s[poz-1]=-1;
		s[poz+1]=-1;
    smax1=0;
	}
	fprintf(out,"%d",smax2);
	
	return 0;
}