#include<fstream>
using namespace std;
long long n,a[1000001],i,j,s=0;
int main()
{
	ifstream f("fractii.in");
	ofstream g("fractii.out");
	f>>n;
	for(i=2;i<=n;i++)
		a[i]=i-1;
	for(i=2;i<=n;i++)
	{
		s=s+a[i];
		for(j=i*2;j<=n;j=j+i)
		a[j]=a[j]-a[i];
	}
	s=s*2+1;
	g<<s;
	return 0;
}