/***************************************************************************
 *   Copyright (C) 2008 by cata,,,   *
 *   cata@cata-laptop   *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/


#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <iostream>
#include <cstdlib>
#include<fstream>
#define dim 1000000
using namespace std;

ifstream f("/home/cata/te/src/fractii.in");
ofstream g("/home/cata/te/src/fractii.out");

void prime_ciur(long long n, int v[])
{long long i,j;
for(i=2;i<=n;i++) v[i]=1;
for(i=2;i<=n;i++)
 for(j=2*i;j<=n;j=j+i)
	v[j]=0;
}

int main(int argc, char *argv[])
{
long long n, b,a,k=0;float nr;
int *v,i;//declararea dinamica a vectorului  
v=new int [dim];
f>>n;
prime_ciur(n,v);

for(b=2;b<=n;b++)
 {
 if(v[b]==1) nr=b-1;
 else
{
 nr=b;
 for(a=2;a*a<=b;a++)
 if(b%a==0 && v[a]==1) nr=(1-1.0/a)*nr;
}
 k=k+2*nr;
	}

g<<k+1;
f.close();
g.close();
delete v;
  return EXIT_SUCCESS;
}