#include <fstream>
using namespace std;

const int VMAX = 1000010;

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

int n;
long long int sol;
int euler[VMAX];

int main() {
	fin >> n;
	for (int i = 2; i <= n; i++)
		euler[i] = i - 1;

	for (int i = 2; i <= n; i++) {
		sol += euler[i];
		for (int j = 2 * i; j <= n; j += i)
			euler[j] -= euler[i];
	}
	fout << 2 * sol + 1 << '\n';

	fout.close();
	return 0;
}