#include <iostream>
#include <fstream>

using namespace std;

int n, a[1000100], i, j, s;

int main()
{
	ifstream f("fractii.in");
	ofstream g("fractii.out");

	f >> n;
	for (j = 1; j <= n; j++)
		a[j] = j - 1;
	for (i = 2; i <= n; i++)
	{
		for (j = i + i; j <= n; j += i)
			a[j] -= a[i];
	}
	for (i = 2; i <= n; i++)
		s += a[i];
	g << s * 2 + 1;
	return 0;
}