#include<fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
long v[1000005];
int main()
{
    long long n,i,j,nr=0;
    
	f>>n;
	for (i=1;i<=n;i++)
	 v[i]=i-1;
	for (i=2;i<=n;i++)
	 for (j=2*i;j<=n;j+=i)
		 v[j]-=v[i];
	for (i=2;i<=n;i++)
 	 nr+=v[i];
	g<<nr*2+1;
	f.close();
	g.close();
	return 0;
}