#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <list>
#include <vector>
using namespace std;

// chack wheather a number n is a natural number
bool checkNaturalNum(int n) {
  int count = 0;
  for (int i = 1; i < n + 1; i++) {
    if (n % i == 0) {
      count++;
    }
  }

  if (count == 2) {
    return true;
  } else {
    return false;
  }
}

int countNaturalNum(int n) {
  int count = 0;
  for (int i = 1; i < n + 1; i++) {
    if (checkNaturalNum(i)) {
      count++;
    }
  }
  return count;
}

int main(int argc, char const *argv[]) {
  int num;
  while (std::cin >> num) {
    std::cout << countNaturalNum(num) << '\n';
  }
  return 0;
}

