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 Haskell (judge verdict: Memory Limit Exceeded)

{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE OverloadedStrings #-}
import qualified Data.ByteString.Char8 as BC
import Data.ByteString (ByteString)
import qualified Data.Set as S
-- Should I implement this myself?
import Control.Monad

data Command = Insert ByteString
             | Find ByteString

fromString :: ByteString -> Command
fromString s = let (cmd:str:_) = BC.words s
                   in
                   case cmd of
                        "insert" -> Insert str
                        "find" -> Find str

follow :: S.Set ByteString -> [Command] -> IO ()
follow s [] = return ()
follow !s (c:cs) = case c of
                       Insert str -> follow (S.insert str s) cs
                       Find str -> do
                           putStrLn $ if str `S.member` s
                                         then "yes"
                                         else "no"
                           follow s cs

main = do
    n <- readLn
    replicateM n BC.getLine >>= follow (S.empty) . map fromString