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 rec suteki_days result x y z =
  match z with
  | 0 -> suteki_days result (x - 1) y 1
  | 1 -> if (y > 0) then suteki_days (result + 1) x (y - 1) 2 else result
  | 2 -> if (x > 0) then suteki_days (result + 1) (x - 1) y 1 else result
  | _ -> raise Not_found;;

let () =
  let raw = read_line () |> split_on_char ' ' |> List.map int_of_string in
  let a = List.fold_left (max) (min_int) raw in
  let b = List.fold_left (min) (max_int) raw in
  suteki_days 0 a b 0 |> print_int; print_newline ();;