#include <iostream>
#include <fstream>
using namespace std;
int nr,v[100],i,j,n;
ifstream f;
ofstream g;
int main()
{
    f.open("fractii.in");
    g.open("fractii.out");
      f>>n;
    for(i=1;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++)
        for(j=i*2;j<=n;j+=i)
            v[j]=v[j]-v[i];
    for(i=2;i<=n;i++)
        nr=nr+v[i];
    g<<2*nr+1<<endl;



return 0;
}