#include <fstream>
using namespace std;

int main() {
	ifstream in("fractii.in");
	long long n, s;
	in >> n;
	s = (long long) n * (n - 1) / 2;
	for (int i = 2; i <= n; i++) {
		s -= (long long) (n - i) / i;
	}

	in.close();

	ofstream out("fractii.out");
	out << (long long) 2 * s + 1;
	out.close();
	return 0;
}