(* O(1) *)
let solve a b c d e k = if e - a <= k then "Yay!" else ":("

let read_int_array n = Array.init n (fun _ -> read_int ())

let _ =
  match read_int_array 6 with
  | [|a; b; c; d; e; k|] -> solve a b c d e k |> print_endline
  | _ -> ()