#include <fstream>
int main()
{
	unsigned i,n, phi[1000000];
	unsigned long long x = 0;
	std::ifstream f("fractii.in");
    f >> n;
    f.close();
	for ( i = 1; i <= n; i++)
		phi[i] = i - 1;
	for (i = 2; i <= n; i++)
	for (unsigned j = 2 * i; j <= n; j += i)
		phi[j] -= phi[i]; 
	for ( i = 2; i <= n; i++)
		x += phi[i] * 2;
	std::ofstream g("fractii.out");
	g << x  + 1;
	g.close();
}