#include <bits/stdc++.h>

using namespace std;

ifstream fin( "fractii.in" );
ofstream fout( "fractii.out" );

#define f first
#define s second

int i,j,phi[1000010],n;
long long ans;

int main()
{
    fin>>n;
    for( i = 1 ; i <= n ; i++ )
        phi[ i ] = i;
    for( i = 2 ; i <= n ; i++ )
    {
        if( phi[ i ] == i )
            for( j = i ; j <= n ; j += i )
                phi[ j ] = phi[ j ] / i * ( i - 1 );
        ans += phi[ i ];
    }
    fout<<ans*2+1;

return 0;
}