#include<fstream.h>
long int n,p,fr,x,nr;
float phi;
int main()
{
 ifstream in("fractii.in");
 ofstream out("fractii.out");
 in>>n;
 for(nr=2;nr<=n;nr++)
 {
   phi=x=nr;
   if(!(x%2))
   {
     while(!(x%2)) x/=2;
     phi/=2;
   }
   p=3;
   while(x>1)
   {
     if(!(x%p))
     {
       while(!(x%p)) x/=p;
       phi*=(1.0-1/(float)p);
     }
     p+=2;
   }
   fr+=phi;
 }
 out<<fr*2+1;
 return 0;
}