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