#include <stdio.h>
int phi[1000000];
int main()
{
	long long i,j,n,rez;
	rez=0;
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%d",&n);
	for (i=1; i<=n; i++)
		phi[i]=i-1;
	for (i=2; i<=n; ++i)
		for (j=2*i; j<=n; j+=i)
			phi[j]=phi[j]-phi[i];
	for (i=1; i<=n; i++)
		rez=rez+phi[i]*2;
	rez++;
	printf("%lld",rez);
}