var n, i, res: integer;
begin
  res:=1;
  readln(n);
  if n mod 2 = 0 then
    for i:=1 to n do
    begin
      if i mod 2 = 0 then
        res:=res*i
    end
   else
    for i:=2 to n do
      if i mod 2 = 1 then
        res:=res*i;
  writeln(res);
end.