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 PHP (judge verdict: Time Limit Exceeded)

<?php
fscanf(STDIN, '%d', $length);
$dictionary = array();

for($i=0; $i<$length; ++$i){
    fscanf(STDIN, '%s %s', $action, $str);
    switch ($action) {
    case 'insert':
        $dictionary=array_merge($dictionary,array($str=>true));
        break;
    case 'find':
        if(isset($dictionary[$str])){
            echo 'yes'.PHP_EOL;
        } else {
            echo 'no'.PHP_EOL;
        }
        break;
    }
}