#include <bits/stdc++.h>
using namespace std;
const int len = 1e5 + 9;
bool prime[len];
void sieve() {
  for (int i = 0; i < len; i++) prime[i] = 1;
  prime[0] = prime[1] = 0;
  int sq = sqrt(len);
  for (int i = 2; i <= sq; i++) {
    if (prime[i]) {
      for (int j = i * i; j <= len; j += i) {
        prime[j] = 0;
      }
    }
  }
}
int n, counter = 0;
bool almost_pr(int num) {
  int c = 0;
  for (int i = 1; i <= num / 2; i++) {
    if (num % i == 0) {
      if (prime[i]) {
        ++c;
      }
    }
  }
  return c == 2;
}
int main() {
  sieve();
  cin >> n;
  for (int i = 6; i <= n; i++) {
    if (almost_pr(i)) {
      ++counter;
    }
  }
  cout << counter;
}
