program fractii;

var x:longint;
		p,i:longint;
    f:text;

function tot(a:longint):longint;
var i:word;
		x:double;
begin
	x:=a;
  for i:=1 to round(sqrt(a)) do
  if (a mod i=0)and(i<>1) then
  x:=x*(1-1/i);
  if (x=a) then x:=x-1;
  tot:=round(x);
end;

begin
  assign(f,'fractii.in');
  reset(f);
  read(f,p);
  close(f);
  for i:=2 to p do
  x:=x+2*tot(i);
  assign(f,'fractii.out');
  rewrite(f);
  write(f,tot(15));
  close(f);
end.