#include<iostream>
using namespace std;

int main(){
 int n,i,j,x,counter;
 cin >> n;
 counter = 0;
 
 for (i = 1; i <= n; i++) {
   x = 0;
   
   for (j = 1; j <= i; j++) {
     if (i % j == 0) x++;
   }
   
   if (x == 2) counter++;
 }
 
 cout << counter << endl;
 
 return 0;
}
