#include <fstream>
int main()
{
    unsigned i, n, phi[999999];
    unsigned long long x = 0;
    std::ifstream f("fractii.in");
    f >> n;
    f.close();
    for (i = 2; i <= n;phi[i]=i, i++);
    for (i = 2; i <= n; i++)
        if (phi[i] == i)
           for (unsigned j = i; j <= n; phi[j] /= i,phi[j]*=i - 1,j+=i);
    for (i = 2; i <= n; x+=phi[i++]*2);
    std::ofstream g("fractii.out");
    g << x + 1;
    g.close();
}