#include<fstream.h>
#include<iostream.h>
int n,w,i,f[100],x,q,phi;
long long s;
int main()
{
	ifstream in("fractii.in");
	ofstream out("fractii.out");
	in>>x;   
	for(n=1;n<=x;n++)
	{
		q=0;
		w=n;
		for(i=2;i*i<=n && w!=1;++i)
   	 	{
			if(w%i==0)             
   		 	{
				q++;
				f[q]=i;
				while(w%i==0) w=w/i;
			}
		}    	
		if(w!=1) f[++q]=w;
		phi=n;	
		for(i=1;i<=q;i++)
			phi=(phi*(f[i]-1))/f[i];
		s=s+(2*phi);
	}
	out<<s-1<<endl;
	return 0;		
}