#include <fstream>
#include  <iostream>
using namespace std;
int main()
{
	ifstream in("fractii.in");
	ofstream out("fractii.out");
	
	int nr = 0, N ,v[100];
	in>>N;
	for(int i=2;i<=N;i++)
	{
	  v[i] = i - 1;
	}
	for(int i = 2;i<=N;i++)
      {
		  for(int j = i + i ; j<=N;j = j + i)v[j] = v[j] - v[i];
	     nr = nr + v[i];
	   }
    nr = nr * 2 + 1;
	out<<nr;
    return 0;
}