#include <iostream>

using namespace std;
struct sziget
{
   int szam;
   int dij;
   int ar;
};
int hasonlit (sziget s[], int i)
{
   if (s[i].ar<s[i-1].ar) return s[i].ar;
   else return s[i-1].ar;
}

int main()
{
    int N;
    cin >>N;
    sziget s[N+1];
    for (int i=1; i<=N; i++)
    {
       cin>>s[i].dij;
       s[i].szam=i;
    }
    s[1].ar=s[1].dij;
    s[2].ar=s[2].dij+s[1].ar;
    int x=3;
    while (x<=N)
    {
       s[x].ar=hasonlit(s, x-1)+s[x].dij;
       x++;
    }
    cout<<s[N].ar;

    return 0;
}