#include <fstream>

using namespace std;

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

const int N_MAX = 1e6;
int phi[N_MAX + 1];

int main() {
    int n;
    long long s;
    fin >> n;
    s = 0;
    for ( int i = 1; i <= n; i++ )
        phi[i] = i;
    for ( int i = 2; i <= n; i++ ) {
        if ( phi[i] == i )
            for ( int j = i; j <= n; j += i )
                phi[j] = phi[j] / i * ( i - 1 );
        s += phi[i];
    }
    fout << 2 * s + 1;
    return 0;
}