let hash s =
  let len = String.length s in
  let rec loop acc = function
      i when i = len -> acc
    | i ->
      let x = match s.[i] with 'A' -> 1 | 'C' -> 2 | 'G' -> 3 |  _  -> 4 in
      loop (acc*5+x) (i+1)
  in loop 0 0

let () =
  let n = read_int () in
  let dic = Array.make (5. ** 12. |> int_of_float) false in
  let rec loop = function
      0 -> ()
    | i ->
      begin match Scanf.scanf "%s %s\n" (fun a b -> a,b) with
          "insert",word -> dic.(hash word) <- true
        | _,word ->
          print_endline
            (if dic.(hash word) then "yes" else "no")
      end;
      loop (i-1)
  in
  loop n