#include <bits/stdc++.h>
using namespace std;
int factor[3001];
void sieve() {
  for (int i = 0; i < 3001; i++) {
    factor[i] = i;
  }
  for (int i = 2; i * i < 3001; i++) {
    if (factor[i] == i) {
      for (int j = i * i; j < 3001; j += i) {
        if (factor[j] == j) factor[j] = i;
      }
    }
  }
}
int main() {
  sieve();
  int n, count = 0;
  cin >> n;
  for (int i = 6; i <= n; i++) {
    int p = i, prev = 0;
    int k = 0;
    while (p != 1) {
      if (prev != factor[p]) {
        k++;
        prev = factor[p];
      }
      p /= factor[p];
    }
    if (k == 2) count++;
  }
  cout << count << endl;
  return 0;
}
