#include <fstream>

using namespace std;

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

int v[100005], w[100005], n, maxim = -1, maxim1 = -1, p;
long long sum, sumtot;

int verific(){
    for(int i = 1; i <= n; i++){
        if(w[i] == 0 && w[i + 1] == 0){
            return 1;
        }
    }
    return 0;
}

int main()
{
    fin>>n;
    for(int i = 1; i <= n; i++){
        fin>>v[i];
    }
    v[n + 1] = v[1];
    while(verific() == 1){
        maxim1 = 0;
        p = 0;
        for(int i = 1; i <= n; i++){
            sum = v[i] + v[i + 1];
            if(sum > maxim1 && w[i] == 0 && w[i + 1] == 0){
                maxim1 = sum;
                p = i;
            }
        }
        w[p] = 1;
        w[p + 1] = 1;
        w[p - 1] = 1;
        w[p + 2] = 1;
        if(p == 1){
            w[n] = 1;
        }
        else if(p == n){
            w[1] = 1;
            w[2] = 1;
        }
        sumtot += v[p] + v[p + 1];
    }
    fout<<sumtot;
    return 0;
}