let rec solve = function
  | [] -> true
  | [_] -> false
  | c1 :: c2 :: s -> c1 = c2 && solve s

let () =
  let w = read_line () in
  Array.init (String.length w) (fun i -> w.[i])
  |> Array.to_list
  |> List.sort compare
  |> solve
  |> (function true -> "Yes" | false -> "No")
  |> print_endline