var f : text;
     nr, n : longint;
     d : array[1..1000] of integer;

 procedure citire;
 var f:text;
 begin
         assign(f,'fractii.in');reset(f);
         readln(f,n);
         close(f);
 end;

 procedure rez;
 var i,j:longint;
 begin
         for i:=2 to n do d[i] := i-1;
         for i:=2 to n div 2 do begin
                 j:=2*i;
                 while j<=n do begin
                         d[j]:=d[j]-d[i];
                         j:=j+i;
                 end;
         end;
         for i:=2 to n do nr := nr + d[i];
         nr := nr*2 + 1;
 end;

 procedure afisare;
 var f:text;
 begin
         assign(f,'fractii.out');rewrite(f);
         writeln(f,nr);
         close(f);
 end;

 begin
         citire;
         rez;
         afisare;
 end.