#include <bits/stdc++.h>
using namespace std;
const int maxx = 3010;
vector<int> almostPrime;
bool primeDivisor(int n) {
  int count = 0;
  for (int i = 2; i <= n; i++) {
    if (n % i == 0) {
      count++;
      while (n % i == 0) n /= i;
    }
    if (count > 2) return false;
  }
  if (count == 2)
    return true;
  else
    return false;
}
void preCalculate() {
  for (int i = 4; i < maxx; i++)
    if (primeDivisor(i)) almostPrime.push_back(i);
}
void print() {
  for (int i = 0; i < almostPrime.size(); i++)
    printf("p = %d\n", almostPrime[i]);
}
int main() {
  preCalculate();
  int n;
  scanf("%d", &n);
  int ans = 0;
  for (int i = 0; almostPrime[i] <= n; i++) ans++;
  printf("%d\n", ans);
  return 0;
}
