/* -*- coding: utf-8 -*-
 *
 * 2750.cc:  No.2750 Number of Prime Factors - yukicoder
 */

#include<cstdio>
#include<vector>
#include<algorithm>
 
using namespace std;

/* constant */

const int MAX_P = 100;

/* typedef */

typedef long long ll;
typedef vector<bool> vb;
typedef vector<int> vi;

/* global variables */

vb primes;
vi pnums;

/* subroutines */

int gen_primes(int maxp) {
  primes.assign(maxp + 1, true);
  primes[0] = primes[1] = false;

  int p;
  for (p = 2; p * p <= maxp; p++)
    if (primes[p]) {
      pnums.push_back(p);
      for (int q = p * p; q <= maxp; q += p) primes[q] = false;
    }
  for (; p <= maxp; p++)
    if (primes[p]) pnums.push_back(p);
  return (int)pnums.size();
}

/* main */

int main() {
  gen_primes(MAX_P);

  ll  n;
  scanf("%lld", &n);

  ll x = 1;
  int c = 0;
  while (x * pnums[c] <= n && x * pnums[c] >= 0) x *= pnums[c++];

  printf("%d\n", c);
  
  return 0;
}