let () =
  let rec make_lst a b = if a = b then [a] else a :: make_lst (a+1) b in
  let a, b = Scanf.scanf "%d %d\n" (fun x y -> x, y) in
  let lst = make_lst a b in
  let ans = List.length (List.filter (fun x -> x = false) [List.mem 23 lst; List.mem 24 lst; List.mem 25 lst]) in
  Printf.printf "%d\n" ans