let solve n m p q =
  let rec solve' left_leaf cur_mon sum_mon =
    if left_leaf <= 0 then
      sum_mon
    else (
      let left_leaf' =
        if cur_mon >= p && cur_mon < p + q then
          left_leaf - m * 2
        else
          left_leaf - m
      and cur_mon' = cur_mon mod 12 + 1 in
      solve' left_leaf' cur_mon' (sum_mon + 1)
    )
  in
  solve' n 1 0

let () =
  let n, m, p, q =
    read_line ()
    |> fun l -> Scanf.sscanf l "%d %d %d %d" (fun n m p q -> (n, m, p, q))
  in
  solve n m p q
  |> string_of_int
  |> print_endline