#include<iostream.h>  
#include<fstream.h>  
#include<math.h>  
   
 int main()  
     {  
     fstream f("fractii.in",ios::in),g("fractii.out",ios::out);  
     long long i,j,nr,v[1000000],n,s=0;  
     f>>n;  
     for(i=2;i<=n;i++)  
         v[i]=i-i; 
     for(i=2;i<=n;i++) 
          for(j=i+i;j<=n;j+=i)
                  v[j]-=v[i];
     for(i=2;i<=n;i++)
                s+=v[i];  
     g<<2*s+1;  
     f.close();g.close();  
     return 0;  
     }