#include<iostream>
using namespace std;
int main()
{
    int n,v[100];
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    fin>>n;
    for(int i=1;i<=n;i++) v[i]=i-1;
    for(int i=2;i<=n;i++)
    {
            rez=rez+v[i];
            for( int j=i+i;j<=n;j=j+i;
            }
     fout<<rez*2+1;
     return 0;
    }