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

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int N;
  cin>>N;
  vector cnt(N+1,0ll);
  ll ans=0;
  for(int i=N;i>1;i--){
    for(int j=i;j<=N;j+=i){
      cnt[i]-=cnt[j];
    }
    ll t=N/i;
    cnt[i]+=t*t;
    ans+=(cnt[i]-t*2+1)/2;
  }
  cout<<ans<<'\n';
}