#include <fstream>
int main()
{
	unsigned i, n, phi[999999];
	unsigned long long x = 0;
	std::ifstream f("fractii.in");
	f >> n;
	f.close();
	for (int i = 1; i <= N; i++) phi[i] = i;

	for (int i = 2; i <= N; i++)
	if (phi[i] == i)
	for (j = i; j <= N; j += i) phi[j] *= (i-1)/i

	for (i = 2; i <= n; i++)x+=phi[i]*2;
	std::ofstream g("fractii.out");
	g << x + 1;
	g.close();
}