#include <iostream>
#include <vector>
#include <string>

using namespace std;
using ll = long long;
using ull = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

vector<int> sieve;
void sieveinit(int N){
  sieve.resize(N+1,0);
  sieve[0] = sieve[1] = 1;
  for(int i=2; i*i<=N; i++) if(sieve[i] == 0){
    for(int j=i*i; j<=N; j++) sieve[j] = 1;
  }
}

int main(){
  int N; cin >> N;
  sieveinit(N);

  vector<int> X(N+1);
  rep(i,N+1) X[i] = i;
  for(int i=2; i*i<=N; i++) if(sieve[i] == 0){
    int sqi = i*i;
    for(int j=sqi; j<=N; j+=sqi) while(X[j] % sqi == 0) X[j] /= sqi;
  }
  
  vector<int> sqsum(N+1,0);
  for(int i=1; i*i<=N; i++) sqsum[i*i]++;
  rep(i,N) sqsum[i+1] += sqsum[i];

  int ans = 0;
  for(int i=1; i<=N; i++){
    ans += sqsum[N / X[i]];
  }
  cout << ans << "\n";
  return 0;
}


struct ios_do_not_sync{
  ios_do_not_sync(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
  }
} ios_do_not_sync_instance;