let () = Scanf.scanf "%s\n%d" @@ fun s k ->
  let s = Array.init (String.length s) (String.get s) in
  let a = Array.init 2 @@ fun i ->
    snd @@
    Array.fold_left (fun (c, (n, b)) c' ->
      (c', if b = 1 || c <> c' then (n, 0) else (n + 1, 1)))
    (s.(Array.length s - 1), (0, i)) s in
  Printf.printf "%d\n" @@
  if snd a.(1) = 1
  then k * fst a.(1)
  else if snd a.(0) = 0
  then fst a.(1) + (k - 1) * fst a.(0)
  else (k / 2) * (fst a.(0) + fst a.(1)) + (k mod 2) * fst a.(1)


