var f,g:Text;  
        v:array[0..1000000]of longint;  
        s:int64;  
        n,i,j:longint;  
    begin  
    assign(f,'fractii.in');  
    assign(g,'fractii.out');  
    reset(f);  
    rewrite(g);  
   read(f,n);  
   for i:=2 to n do v[i]:=i-1;  
   for i:=2 to n do  
     for j:=2 to n div i do  
       dec(v[i*j],v[i]);  
   for i:=2 to n do inc(s,v[i]);  
   write(g,s*2+1);  
   close(f);  
   close(g);  
   end.