let () =
  let open Hashtbl in
  let n = read_int () in
  let tbl = create ~random:true n in
  let rec doit i =
    if i < n then begin
      match Scanf.scanf "%s %s\n" (fun x y -> (x, y)) with
      | ("insert", x) -> (add tbl x true; doit (i + 1))
      | ("find", x) -> (print_endline (if mem tbl x then "yes" else "no"); doit (i + 1))
      | _ -> exit 1
    end
  in
  doit 0