#include <iostream>

using namespace std;
int a,b,i,x,n;
int main()
{
    cin>>n;
    cin>>a>>b;

    b=b+a;

    for (i=3;i<=n;++i)
    {
        cin>>x;

        if(a<b) x=x+a;
        else x=x+b;
        a=b;
        b=x;
    }

    cout<<b;
    return 0;
}