#include<fstream>
#include<cmath>
#include<iostream>

using namespace std;

int main()
{
	ifstream in("fractii.in");
	ofstream out("fractii.dat");
	int nr_citit;//numarul citit din fisier
	int vec[100001];//impunerea restrictiei
	int i,j;//variabila de contor
	int suma=0;//variabila ce detine nr de fractii din sir
	in>>nr_citit;
	for(i=1;i<=nr_citit;i++)
		vec[i]=i-1;
	for(i=2;i<=nr_citit;i++)
	{
		for(j=2*i;j<=nr_citit;j=j+i)
		{
			vec[j]=vec[j]-vec[i];
		}
	}
	for(i=2;i<=nr_citit;i++)
		suma+=vec[i];
	cout<<2*suma+1;
	cout.flush();
	//in.close();
	//out.close();
	return 0;




}