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 Ruby (judge verdict: Wrong Answer)

def dictionary(orders)
  str = ""
  length = orders.length
  for i in 0..(length-1)
    if orders[i][0] == "insert"
      str += orders[i][1]
    elsif orders[i][0] == "find"
      if str.index(orders[i][1]) == nil
        puts "no"
      else
        puts "yes"
      end
    else
      puts "error!"
    end
  end
end

n = gets.chomp.to_i
orders = []
n.times do
  order = gets.chomp.split
  orders.push(order)
end
dictionary(orders)