Problem:
Search III

Your task is to write a program of a simple dictionary which implements the following instructions:

insert str: insert a string str in to the dictionary

find str: if the distionary contains str, then print 'yes', otherwise print 'no'

Input

In the first line n, the number of instructions is given. In the following n lines, n instructions are given in the above mentioned format.

Output

Print yes or no for each find instruction in a line.

Constraints

A string consists of 'A', 'C', 'G', or 'T'

1 ≤ length of a string ≤ 12

n ≤ 1000000

Sample Input 1

5
insert A
insert T
insert C
find G
find A

Sample Output 1

no
yes

Sample Input 2

13
insert AAA
insert AAC
insert AGA
insert AGG
insert TTT
find AAA
find CCC
find CCC
insert CCC
find CCC
insert T
find TTT
find T

Sample Output 2

yes
no
no
yes
yes
yes

Notes

Template in C

Solution in OCaml (judge verdict: Accepted)

open Scanf

let () =
  let n = read_int () in
  let dic = Hashtbl.create n in
  let f c a =
    if c = "insert" then Hashtbl.add dic a true
    else if
      try Hashtbl.find dic a with _ -> false then print_endline "yes"
    else print_endline "no" in
  let rec loop x =
    if x = 0 then ()
    else let (c, a) = sscanf (read_line ()) "%s %s" (fun x y -> (x, y)) in
         f c a ; loop (x-1)
  in loop n