open Num


let readln_t2_by f =
  let ( @@ ) lst n = List.nth lst n in
  read_line () |>
  Str.split (Str.regexp_string " ") |>
  List.map f |>
  fun lst -> (lst @@ 0, lst @@ 1)



let () =
  let n, k = readln_t2_by num_of_string in
  let ans = floor_num (n // (k +/ Int 1)) +/ (Int 1) in
  print_endline (string_of_num ans)