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