#!/usr/bin/env python
# -*- coding:utf-8 -*-
#from __future__ import print_function
import time
import sys
import io
import re
import math
#start = time.clock()
#i = 0
a,b=[],[]
check = re.compile('insert')
n=input()
#while True:
for x in xrange(n):
    (i,f)=map(str, raw_input().split())
    if check.search(i):
        a.append(f)
    else:
#        b.append(f)
#print a
#print b
#for y in b:
        if f in a:
            print 'yes'
        else:
            print 'no'