open Scanf
open Printf

let n = scanf "%d\n" (fun x -> x)
let dict = Array.make n "NIL"

let to_num = function
 'A' -> 1
 |'C' -> 2
 |'G' -> 3
 |_ -> 4

let to_key s =
 let len_s = String.length s in
 let rec getKey i p sum =
  if i = len_s then sum
  else
   let sum2 = sum + p * to_num s.[i] in
   getKey (i+1) (p*5) sum2
 in
 getKey 0 1 0

let h1 key = (to_key key) mod n
let h2 key = (1 + (to_key key)) mod (n-1)
let h key i = (h1 key + i * h2 key) mod n

let insert key =
 let rec insert_key i =
 let j = h key i in
 if dict.(j) = "NIL" then (dict.(j) <- key)
 else insert_key (i+1)
in insert_key 1

let find key = 
 let rec find_key i =
  let j = h key i in
  if dict.(j) = key then true
  else if dict.(j) = "NIL" || i >= n then false
  else find_key (i+1)
 in find_key 1

let () =
 let rec input_s i = 
  if i = n then ()
  else
   let o, s = scanf "%s %s\n" (fun x y -> (x, y)) in
   if o.[0] = 'i' then (insert s; input_s (i+1))
   else
    if find s then (printf "yes\n"; input_s (i+1))
    else (printf "no\n"; input_s (i+1))
 in input_s 0