#include <fstream>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

int i,j,n;
int v[1000001];
long long m;

int main()
{
   f>>n;
   v[1]=1;

   for (i=2;i<=n;i++)
    v[i]=i-1;

   for (i=2;2*i<=n;i++)
    for (j=i*2;j<=n;j+=i)
     v[j]-=v[i];

    for (i=1;i<=n;i++)
     m+=v[i];

    g<<2*m-1;

   f.close();
   g.close();
}