#include <bits/stdc++.h>
using namespace std;
long long const md = 1000000007;
double EPS = 1e-9;
int dcmp(double x, double y) { return fabs(x - y) <= EPS ? 0 : x < y ? -1 : 1; }
long long fastpower(long long x, long long y) {
  long long res = 1;
  while (y) {
    if (y & 1) res *= x;
    res %= md;
    y >>= 1;
    x *= x;
    x %= md;
  }
  return res;
}
long long inv(long long x) { return fastpower(x, md - 2); }
void solve() {
  int n;
  cin >> n;
  int ans = 0;
  for (int i = 6; i <= n; i++) {
    int cnt = 0;
    int x = i;
    for (int j = 2; j * j <= x; j++) {
      bool flage = false;
      while (x % j == 0) {
        if (!flage) {
          cnt++;
          flage = true;
        }
        x /= j;
      }
    }
    if (x > 1) cnt++;
    if (cnt == 2) {
      ans++;
    }
  }
  cout << ans << endl;
}
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
