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

ifstream fin("ciur.in");
ofstream fout("ciur.out");
const int TWO = 2;

int main() {
  int n;
  fin >> n;
  int final_counter = 0;
  for (int i = 1; i <= n; ++i) {
    int prime_check = 0;
    for (int j = 1; j <= i; ++j) {
      if (i % j == 0) {
        ++prime_check;
      }
    }
    if (prime_check == TWO) {
      ++final_counter;
    }
  }
  fout << final_counter;
  return 0;
}