#include <bits/stdc++.h>
using namespace std;
int prime[3005], np;
bool mark[3005];
int pdivs[3005];
void Sieve() {
  int i, j, len = sqrt(3005) + 1;
  for (i = 3; i <= 3005; i += 2)
    if (!mark[i]) {
      prime[np++] = i;
      if (i <= len)
        for (j = i * i; j <= 3005; j += i) mark[j] = true;
    }
}
void pdivss() {
  int i, j, k = 0;
  for (i = 2; i < 3005; i += 2) pdivs[i]++;
  ;
  while (prime[k] && k < np) {
    for (i = prime[k]; i < 3005; i += prime[k]) {
      pdivs[i]++;
    }
    k++;
  }
}
int main() {
  Sieve();
  pdivss();
  int n;
  cin >> n;
  int counter = 0;
  for (int i = 1; i <= n; i++)
    if (pdivs[i] == 2) counter++;
  cout << counter << endl;
  return 0;
}
