#include <fstream>

using namespace std;

int main()
{
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");
	int n;
	fin >> n;
	int a[n + 2];
	int i, j;
	unsigned long long nrf;
	for(i = 2; i <= n; i++)
		a[i] = i - 1;
	for(i = 2; i <= n; i++)
	{
		nrf += a[i];
		for(j = 2 * i; j <= n;j += i)
			a[j] -= a[i];
	}
	fout << nrf * 2 + 1;
	return 0;
}