#include <fstream>
#include <math.h>

using namespace std;

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

int main(){
	int n,nr=0,j,p,phi,aux;
	fin>>n;
	for (int i=1; i<=n; ++i){
		j=2;
		phi=1;
		aux=i;
		while (aux!=1){
			p=0;
			while (aux%j==0){
				p++;
				aux/=j;
			}
			if (p!=0)
				phi*=(j-1)*pow(j,p-1);
			j++;
		}
		nr+=phi;
	}
	fout<<nr*2-1;
	fin.close();
	fout.close();
	return 0;
}