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

本题采用的是双散列结构，其他的散列方式还没有尝试，以后有时间可以套进去试一下。
本题主要分为两部分：
1.将字符串转换通过合适的方法转换为一个整数值，这个合适的意思是尽量将元素分散，均匀分布
2.将这个整数值通过双散列法转换为一个散列值