package ciur;
import java.io.*;
import java.util.*;
import java.lang.*;
class Ciur {

    public Scanner x;
    String a = "";
    int n;
    int nr = 0;
     boolean b ;
    public void openFile(){
        try{
            x = new Scanner(new File("ciur.in"));
        }catch(Exception e){
            System.out.println("nu exista fisierul!");
        }
    }
    public void readFile(){

        while(x.hasNext()){
            a = x.next();
        }
        n = Integer.parseInt(a);

    }
    public void closeFile(){
        x.close();
    }

    public int ciur(){

        for(int i = 2 ; i <= n ; i++){
            b = true;
            for (int j = 2 ; j <= n ; j++){
                if ((i % j == 0) && (i != j)){
                    b = false;
                    break;
                }
                if (b == false){
                    break;
                }
            }

            if(b == true){
                nr = nr + 1;
            }
        }

        return nr;


    }
    public static void main(String [] args){
        Ciur r = new Ciur();
        r.openFile();
        r.readFile();
        r.closeFile();
        int nr = r.ciur();

        scriere s = new scriere();
        s.openFile();
        s.addRecords(nr);
        s.closeFile();
    }
}

class scriere {
    public Formatter x;

    public void openFile(){
        try{
        x = new Formatter("ciur.out");
        }catch(Exception e){
            System.out.println("Nu s-a gasit fisierul");
        }
    }
    public void addRecords(int nr){
        x.format("%s",nr);
    }

    public void closeFile(){
        x.close();
    }
}