#include <iostream>
#include <fstream>

using namespace std;

ifstream f("date.in");
ofstream g("date.out");

int n, i, j, *v;
long long sum;

int main()
{
	f >> n;
	v = new  int[n + 1];
	for (i = 1; i <= n; i++)
		v[i] = i - 1;
	for (i = 1; i <= n; i++)
		for (j = 2 * i; j <= n; j += i)
			v[j] -= v[i];
	for (i = 1; i <= n; i++)
		sum += v[i];
	g << 2 * sum + 1;

	return 0;
}