let list_of_str s =
  let rec f i = if i >= String.length s then [] else s.[i] :: f (i+1) in f 0

let rec solve = function
  | [] -> "YES"
  | 'e'::'r'::'a'::'s'::'e'::'r'::xs | 'e'::'r'::'a'::'s'::'e'::xs
  | 'd'::'r'::'e'::'a'::'m'::'e'::'r'::'a'::'s'::'e'::'r'::xs
  | 'd'::'r'::'e'::'a'::'m'::'e'::'r'::'a'::'s'::'e'::xs
  | 'd'::'r'::'e'::'a'::'m'::'e'::'r'::xs
  | 'd'::'r'::'e'::'a'::'m'::xs
    -> solve xs
  | _ -> "NO"

let () = Scanf.scanf "%s" list_of_str |> solve |> print_endline
