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