#include <fstream>
#define nmax

using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int N;
int main()
{int nrFrc = 0, jum, posibil, i, j;
    f>>N;
    nrFrc = 2 * N - 1;
    jum = N / 2 + 1;
    for(i = 2; i <= jum; ++i){
        posibil = (N - i) * 2;
        for(j = i + i; j <= N; j += i){
            posibil -= 2;
        }
        nrFrc += posibil;
    }
    g<<nrFrc << '\n';
    return 0;
}