#include <iostream>
#include <fstream>

using namespace std;

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

int main()
{
    int n, i, j, s;
    in >> n;
    s = n;
    for (i = 2; i <= n; i++)
    {
        for (j = 1; j <= n; j++)
        {
            if (j % i != 0)
                ++s;
        }
    }
    out << s;
    return 0;
}