//fractii. 
#include<iostream.h>
#include<fstream.h>
ifstream f("fractii.in");
ofstream g("fractii.out");
long i,j,n,s,phi[1000000];
//functia phi calculeaza numarul de numere prime cu n mai mici ca n
/*long phi(long x)
{
	for(i=1;i<=x;i++)
	{
		p=x;
		q=i;
		while(q)
		{
			r=p%q;
			p=q;
			q=r;
		}
		if(p==1)
			k++;
	}
	return k;
}*/
int main()
{
	f>>n;
	for(i=1;i<n+1;i++)
		phi[i]=i-1;
	for(i=2;i<n+1;i++)
		for(j=2*i;j<=n;j+=i)
			phi[j]-=phi[i];
	for(j=1;j<=n;j++)
		s+=phi[j];
	g<<2*s+1<<" ";
/*	for(long j=1;j<=n;j++)
		a[j]=phi(j);
		//cout<<phi(j)<<" ";
	g<<2*a[n]-1;*/
return 0;
}