#include <fstream.h>
int main()
{	long n,k,j,i;
	unsigned int nr_fractii=1;
   ifstream f("fractii.in");
   ofstream f2("fractii.out");
   // ia numarul
   f>>n;
   nr_fractii=n*(n-1)+1;
   j=2;
   k=2*j;
   while(k<=n)
   {
    nr_fractii--;
    j++;
    k=2*j;
   }  
  //nr_fractii+=(n/2)-1;  
   for(i=3;i<=n/2;i+=2)
  {j=2;
   k=i*j;
   while(k<=n)
   {
    nr_fractii--;
    j++;
    k=i*j;
   }  
  }
//}
   f2<<nr_fractii;
   return 0;
}