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 cooking a b n m =
  (min a b) + (if (a > b) then ((a - b) / n) else ((b - a) / m));;

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 n = List.nth raw 2 in
  let m = List.nth raw 3 in
  cooking a b n m |> print_int; print_newline ();;