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 Scala (judge verdict: Runtime Error)

import scala.io.StdIn.{readInt,readLine}
import scala.collection.mutable.ArrayBuffer

object Main extends App {
  type Set = String => Boolean

  def contains(s:Set, elem:String):Boolean = s(elem)
  def singletonSet(elem:String):Set = x => x==elem
  def union(s:Set, t:Set):Set = x => contains(s,x) || contains(t,x)

  val n = readInt

  def loop(i:Int, s:Set, a:ArrayBuffer[String]):ArrayBuffer[String] =
    if(i>n) a
    else {
      val l = readLine.split(" ")
      val isInsert = l(0)(0) == 'i'
      val newSet = if(isInsert) union(singletonSet(l(1)),s) else s
      if(!isInsert && contains(s,l(1))) a += "yes"
      else if(!isInsert && !contains(s,l(1))) a+="no"
      loop(i+1, newSet, a)
    }
  println(loop(1, singletonSet("-"),new ArrayBuffer[String]()).mkString("\n"))
}