#include <fstream>
using namespace std;
ifstream cin("fractii.in");
ofstream cout("fractii.out");
int main()
{
	long n, rez=0, i, j;
	cin>>n;
	long euler[n+1];
	for (i=2;i<=n;i++)
		euler[i]=i-1;
	for (i=2;i<=n;i++){
		rez=rez+euler[i];
		for (j=2*i;j<=n;j+=i)
			euler[j]=euler[j]-euler[i];
	}
	cout<<rez*2+1;
	cin.close();
	cout.close();
}