/* -*- coding: utf-8 -*-
 *
 * 1514.cc:  No.1514 Squared Matching - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 50000000;
const int MAX_P = 7100;

/* typedef */

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

/* global variables */

bool primes[MAX_P + 1];
int ts[MAX_N + 1];

/* subroutines */

int gen_primes(int maxp, vi &pnums) {
  memset(primes, true, sizeof(primes));
  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() {
  vi pnums;
  int pn = gen_primes(MAX_P, pnums);

  int n;
  scanf("%d", &n);

  for (int i = 1; i <= n; i++) ts[i] = i;

  for (int i = 0; i < pn; i++) {
    int pi = pnums[i];
    if (pi * pi > n) break;

    int pp = pi * pi;
    for (ll pe = pp; pe <= n; pe *= pp)
      for (int q = pe; q <= n; q += pe) ts[q] /= pp;
  }

  ll sum = 0;
  for (int i = 1; i <= n; i++)
    sum += floor(sqrt((n + 0.5) / ts[i]));

  printf("%lld\n", sum);
  return 0;
}