#include <fstream.h>
int nre[1000000];
int main()
{	long n,k,j,i;
	unsigned int nr_fractii=1;
   ifstream f("fractii.in");
   ofstream f2("fractii.out");
   // ia numarul
   f>>n;
   j=2;
   k=i*2;
   while(k<n)
   {
    nr_fractii++;
    j++;
   
   }  
   for(i=3;i<=n/2;i+=2)
  {j=2;
   k=i*j;
   while(k<n)
   {
    nr_fractii++;
    j++;
   
   }  
  }
   f2<<nr_fractii;
   return 0;
}