#include<fstream.h>
int v[1000001];
int main()
{
	int n,i,j,e,ax,d;
	long long nr;
	fstream f,g;
	f.open("fractii.in",fstream::in);
	g.open("fractii.out",fstream::out);
	f>>n;
	nr=0;
	for (i=2;i<=n;i++)
	{
		v[i]=v[i]+i-1;
		for (j=2*i;j<=n;j+=i)
			v[j]-=v[i];
		nr+=v[i];
	}
	g<<nr*2+1;
	g.close();
	return 0;
}