#include <fstream>
#include <vector>

using namespace std;

int main(void)
{
    long n;
    long rezultat = 1;
    vector<long> v;
    v.push_back(0);
    ifstream f("fractii.in", ifstream::in);
    ofstream g("fractii.out", ofstream::out);

    f >> n;

    for (long i = 1; i <= n; i++)
        v.push_back(i - 1);
    for (long i = 2; i <= n; ++i)
    {
        rezultat += 2 * v[i];
        for (long j = 2 * i; j <= n; j += i)
            v[j] -= v[i];
    }

    g << rezultat;
    f.close();
    g.close();

    return 0;
}