#include<bits/stdc++.h>
using namespace std;

ifstream fin("oo.in");
ofstream fout("oo.out");

/*
void gen(int n, int omax, int gaini[])
{
    srand(time(NULL));
    for(int i=1; i<=n; i++)
        gaini[i]=rand()%(omax+1);
}
*/

int rez(int n, int gaini[])
{
    int sum=0;
    for(int i=1; i<=n; i++)
    {
        int a=i-1, b=i+1;
        if(a==0) a=n;
        if(gaini[i]+gaini[i+1]>gaini[a]+gaini[b])
        {
            //cout<<i<<' '<<i+1<<' '<<'('<<gaini[i]+gaini[i+1]<<")\n";
            sum+=gaini[i]+gaini[i+1];
            gaini[a]=0;
            gaini[b]=0;
        }
    }
    return sum;
}

int main()
{
    int n, o, gaini[100001];
    fin>>n;
    for(int i=1; i<=n; i++) fin>>gaini[i];
    //cin>>n>>o;
    //gen(n, o, gaini);
    //for(int i=1; i<=n; i++) cout<<gaini[i]<<' ';
    //cout<<endl;
    //cout<<rez(n, gaini);
    fout<<rez(n, gaini);
}