#include <fstream>
int main()
{
	unsigned n, x = 0, phi[999999];
	std::ifstream f("fractii.in");
	f >> n;
	f.close();
	for (int i = 2; i <= n; phi[i++] = i - 1);
	for (int i = 2; i <= n; i++)
	for (int j = 2 * i; j <= n; j += i)phi[j] -= phi[i];
	for (int i = 2; i <= n; x += phi[i++]);
	std::ofstream g("fractii.out");
	g << x * 2 +1;
	g.close();
}