#include <fstream>
#include <iostream>
using namespace std;

ifstream fin("ciur.in");
ofstream fout("ciur.out");

int n , i , j , s, nr;

int main() {
    
    fin>> n; i = 2; j = 1;
    
    while ( i <= n ){
        
        while ( j <= i ){
            
            if ( i % j == 0 ){
                
                s = s + 1;
                
            }
            
            j = j + 1;
        }
        
        if ( s == 2 ){
            
            nr = nr + 1;
            
        }
        
        i = i + 1;
        j = 1;
        s = 0;
    }
    
    fout<< nr;
    
    return 0;
}