#include<fstream>
#include <vector>
#include <iostream>
#include <math.h>
using namespace std;

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

vector<int> solution;



int main()
{
	long long output = 0;
	int n = 0;
	fin >> n;
	solution.resize(n + 1);
	for (int i = 2; i <= n; i++)
	{
		solution[i] = i - 1;
	}
	for (int i = 2; i <= n; ++i)
	{
		for (int j = i + i; j <= n; j += i)
		{
			solution[j] -= solution[i];
		}
		output += 2 * solution[i];
	}
	fout << output + 1;

}