#include <iostream>
#include <fstream>
using namespace std;

int ggt(int a, int b)
{
	if (a%b == 0)
		return b;
	return ggt(b,a%b);
}

int euler(int n)
{
	long long dummy = n;
	int p=2,ct;
	//cout << dummy << endl;
	while (n>1)
	{
		ct=0;
		while (n%p == 0)
			n = n/p,ct++;
		if (ct>0)
			dummy = dummy/p*(p-1);
		//cout << p << " " << ct << " " << dummy <<  endl;
		p++;
	}
	return dummy;
}

int main(void)
{
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");
	int a,x,ct=0;
	fin>>a;
	for(x=2;x<=a;x++)
	{
		
		ct += euler(x);		
//		cout << x << " " << euler(x) << endl;
	}
	ct=2*(ct)+1;
	fout<<ct;
	return 0;
}