#include <fstream>

using namespace std;

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

int imp(int x, int y) //cate numere pana la x (inclusiv) se impart la y
{
    int c=0,a=1;
    while (a<x)
    {
        a*=y;
        c+=x/a;
    }
    return c;
}

main()
{
    int n,x=0,c;
    cin >> n;
    c=n;
    for (int i=2; i<=n; i++)
    {
        //x=imp(n,i);
        //cout << i << ' ' << x << endl;
        c+=n-n/i;
    }
    cout << c << endl;
}