#include <iostream>
#include <fstream>
#define nmax 1000005
using namespace std;

ifstream in("fractii.in");
ofstream out("fractii.out");

unsigned long long n, sol;
int v[nmax];

int main()
{
	in >> n;
	for (int i = 2; i <= n; v[i] = i - 1, ++i);
	for (int i = 2; i <= n / 2; ++i)
		for (int j = 2 * i; j <= n; v[j] -= v[i], j += i);
	for (int i = 2; i <= n; sol += v[i++]);
	out << 2 * sol + 1;
	system("pause");
}