#include<fstream>

using namespace std;

FILE*in;
ofstream out("fractii.out");

long n;
long nr_fractii;

void read()
{
    in=fopen("fractii.in", "r");

    fscanf(in, "%ld", &n);
}

void solve()
{
    nr_fractii=1+n*(n-1); // numarul maxim posibil

    for (long i=2; i<=n/2; i++)
        if (n / i > 1)
            nr_fractii-=(n/i-1)*2;
}

void show()
{
    out<<nr_fractii;
}

int main()
{
    read();
    solve();
    show();

    return 0;
}