let split_on_char sep s =
  let r = ref [] in
  let j = ref (String.length s) in
  for i = String.length s - 1 downto 0 do
    if String.unsafe_get s i = sep then begin
      r := String.sub s (i + 1) (!j - i - 1) :: !r;
      j := i
    end
  done;
  String.sub s 0 !j :: !r;;

let ousama a b c d =
  if ((a = c) || (b = d)) then 1
  else if (abs (a - c) < 3) && (abs (b - d) < 3)
          && (((abs (a - c)) + (abs (b - d))) < 3) then 1
  else 2;;

let () =
  let raw = read_line () |> split_on_char ' ' |> List.map int_of_string in
  let a = List.nth raw 0 in
  let b = List.nth raw 1 in
  let c = List.nth raw 2 in
  let d = List.nth raw 3 in
  ousama a b c d |> print_int; print_newline ();;