#include <iostream>
#include <fstream>
using namespace std;

 ifstream f("fractii.in");
 ofstream g("fractii.out");
int v[1000005];
int i,j,n,x,y;
long long nr=0;

int main()
{
    f>>n;
    for(i=1;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++)
    {x=v[i];
    for(j=i*2;j<=n;j+=i)
       {y=v[j];y-=x;v[j]=y;}
        nr+=x;}

   g<<2*nr+1;


}