#include <bits/stdc++.h>
using namespace std;
ifstream fin ("fractii.in") ;
ofstream fout ("fractii.out") ;
long long n , i , j , a[1000005] ;
long long sum , nr ;
const int Max = 1e6 ;
int main()
{
    fin >> n ;
    for ( i = 1 ; i <= Max ; i ++ )
        a[i] = i ;
    for ( i = 2 ; i <= Max ; i ++ )
    {
        if ( a[i] == i )
        {
            a[i] -- ;
            for ( int j = 2 ; j * i <= Max ; j ++ )
                a[j*i] = a[j*i] / i * ( i - 1 ) ;
        }
    }
    for ( i = 1 ; i <= n ; i ++ )
        sum += a[i] ;
    nr = n * n ;
    fout << sum * 2 - 1 ;

    return 0;
}