#include<fstream>

using namespace std;

int v[1000000];
int main ()
{

    ifstream f("fractii.in");
    ofstream g("fractii.out");

    int i ,j , N;
    long long nr = 0;
    f >> N;
    for ( i = 0; i <= N; ++i)
        v[i] = i - 1;
    for ( i = 1; i <= N; ++i)
        {
            for (j = 2 * i; j <= N; j = j + i)
            v[j] = v[j] - v[i];
            nr = nr + v[i];
        }
    g << 1 + 2 * nr;
}