#include<fstream>
#define dmax 1000002
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int nr[dmax],n;
long int k;
int main()
{	int i,j;
	in>>n;
	in.close();
	for(i=1;i<=n;i++)
		nr[i]=i-1;
	for(i=2;i<=n;i++)
	{	for(j=2*i;j<=n;j+=i)
			nr[j]-=nr[i];
		k+=2*nr[i];
	}
	k++;
	out<<k;
	out.close();
	return 0;
}