#include<fstream>
using namespace std;
ifstream f("ciur.in");
  ofstream g("ciur.out");
unsigned char x[250001];

unsigned long dabit(long n)//returneaza bit-ul corespunzator numarului n
{
  unsigned char c=x[1+(n-1)/8];
  int i;
  for(i=1;i<1+(n-1)%8;i++)c=c/2;
  return c%2;
}

void punebit(long n)//pune bit-ul corespunzator numarului n pe valoarea 1
{
  //in x["octet"], pe pozitia "bit" pun valoarea 1
  long octet=1+(n-1)/8;
  int bit=1+(n-1)%8,i;
  unsigned char doi=1;//calcul masca=peste tot 0, doar pozitia "bit"=1
  for(i=1;i<bit;i++)doi=doi*2;
  x[octet]=x[octet]|doi;//sau logic la nivel de bit
}


int main()
{
  
  unsigned long n,i,j,l=0;
  f>>n;
  for(i=1;i<=n/8;i++)x[i]=0;
  for(i=2;i<=n/2;i++)
    if(dabit(i)==0)
      for(j=2*i;j<=n;j=j+i)punebit(j);
  for(i=2;i<=n;i++)
    if(dabit(i)==0)l++;
  g<<l;
  f.close();
  g.close();
  return 0;
}