#include<stdio.h>
#include<math.h>
long ciur(long n)
{
	long e=0,d=2,phi=n,lim;
	lim=sqrt(n);
	while (d<=lim&&n>1)
	{
		e=0;
		while (n%d==0)
		{
			e++;
			n=n/d;
		}
		if (e)
			phi=phi/d*(d-1);
		d++;
	}
	if (n>1)
		phi=phi/n*(n-1);
	return phi;
}
int main()
{
	long n,i;
	long long s=0;
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%ld",&n);
	for (i=2;i<=n;i++)
		s=s+ciur(i);
	printf("%lld",s*2+1);
}