/*
 * main.cpp
 *
 *  Created on: Feb 16, 2015
 *      Author: levi
 */

#include <fstream>
using namespace std;

int main() {

	ifstream fin;
	ofstream fout;

	fin.open("fractii.in");

	int phi[1000001];
	int n, result = 0;
	fin >> n;

	fin.close();

	fout.open("fractii.out");
	++n;
	for (int i=1; i<n; ++i) {
		phi[i] = i-1;
	}
	for (int i=2; i<n; ++i) {
		for (int j = 2*i; j<n; j+= i) {
			phi[j] -= phi[i];
		}
	}

	for (int i=2; i<n; ++i) result += phi[i];

	result = result*2 + 1;
	fout << result;
	fout.close();

	return 0;
}