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 Python (judge verdict: Runtime Error)

def main():
    n = input()
    D = []
    O = []
    for i in range(n):
        c, k = raw_input().split()
        if c == 'insert':
            D.append(k)
        else:
            O.append(search(D,k))

    for item in O:
        print item

    return 0


def search(D,k):
    Dc = D[:]
    if Dc == []:
        return 'no'
    else:
        d = Dc.pop()
        if d == k:
            return 'yes'
        else:
            return search(Dc,k)


if __name__ == "__main__":
    main()