#include <bits/stdc++.h>
using namespace std;
const int NN = 1e5;
bool notPrime[NN];
void sieve() {
  notPrime[0] = notPrime[1] = 1;
  for (int i = 2; i < NN / i; i += 1 + (i & 1))
    if (notPrime[i] == 0)
      for (int j = i * i; j < NN; j += i) notPrime[j] = 1;
}
vector<int> primes;
int a[3001];
int main() {
  int n, s = 0, i, j;
  scanf("%d", &n);
  for (i = 2; i <= n; i++) {
    if (a[i] == 0)
      for (j = i; j <= n; j += i) a[j]++;
    if (a[i] == 2) s++;
  }
  printf("%d\n", s);
  return 0;
}
