/* 
 * File:   main.cpp
 * Author: virtualdemon
 *
 * Created on March 23, 2010, 2:14 PM
 */
#include <cstdio>
#include <cstdlib>

/*
 * 
 */
using namespace std;
int phi[ 1000010 ];
int main( void )
{
    int N, i, j, s=1;
    fscanf( fopen( "fractii.in", "rt" ), "%d", &N );
    for( i=1; i <= N; ++i )
        phi[i]=i-1;
    for( i=2; i <= N; ++i )
    {
        for( j=i*2; j <= N; j+=i )
            phi[j]-=phi[i];
        s+=2*phi[i]; 
    }
    fprintf( fopen( "fractii.out", "wt" ), "%d", s );
    return EXIT_SUCCESS;
}