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 C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AOJ {
    class ALDS1_4_C {
        static HashSet<string> dic = new HashSet<string>();
        static void Main(string[] args) {
            int n = int.Parse(Console.ReadLine());
            for(int i = -0; i < n; i++) {
                string[] input = Console.ReadLine().Split();
                if (input[0] == "insert") dic.Add(input[1]);
                else {
                    string output = dic.Contains(input[1]) ? "yes" : "no";
                    Console.WriteLine(output);
                }
            }
        }
    }
}