#include <bits/stdc++.h>
using namespace std;


int main() {
  int n; cin >> n;

  vector<int> sn(n + 1);
  for(int i = 1, s = 1; i <= n; ++i){
    while(s*s <= i) ++s;
    sn[i] = s - 1;
  }

  int m = sn[n];

  vector<bool> ps(m + 1, true);
  ps[0] = ps[1] = false;

  vector<int> odd(n + 1);
  iota(odd.begin(), odd.end(), 0);

  int ans = 0;

  for(int i = 2; i*i <= n; ++i){
    if(!ps[i]) continue;
    for(int j = i*i; (int64_t)j*j <= n; j += i) ps[j] = false;

    for(int64_t p = i*i; p <= n; p *= i*i){
      for(int q = p; q <= n; q += p) odd[q] /= i * i;
    }
  }

  for(int a = 1; a <= n; ++a){
    ans += sn[n / odd[a]];
  }

  cout << ans << endl;
}