#include <fstream.h>

int cmmdc(long a, long b)
{  long r;
	if(a!=1)
  {while(b)
   {	r=a%b;
      a=b;
      b=r;
   }
   return a;}
   else {
        return 1;
   }
}
int nre[1000000];
int main()
{	long n, p, q,k,j,i;
	unsigned int nr_fractii=1;
   ifstream f("fractii.in");
   ofstream f2("fractii.out");
   // ia numarul
   f>>n;
   nre[2]=1;
   for(i=2;i<=n/2;i++)
  {j=2;
   k=i*j;
   while(k<n)
   {
    nr_fractii++;
    nre[k]=0;
    j++;
   
   }  
  }
   f2<<nr_fractii;
   return 0;
}