var i,j,n:longword;
    sum:qword;
    ph:array[1..2000001] of int64;

begin
    // assign(input,'fractii.in'); reset(input);
     read(input,n); close(input);
     for i:=1 to n do ph[i]:=i-1;
     for i:=2 to n do
      begin
          j:=2*i;
          repeat
             ph[j]:=ph[j]-ph[i];
             inc(j,i);
          until j>n;
     end;
   sum:=1;
   for i:=1 to n do sum:=sum+(2*ph[i]);
  // assign(output,'fractii.out'); rewrite(output);
   write(output,sum); close(output);

end.