trie树Message Flood

Message Flood

Time Limit: 1500MS Memory limit: 65536K

题目描述

Well, how do you feel about mobile phone? Your answer would
probably be something like that "It's so convenient and benefits
people a lot". However, If you ask Merlin this question on the New
Year's Eve, he will definitely answer "What a trouble! I have to
keep my fingers moving on the phone the whole night, because I have
so many greeting message to send!" Yes, Merlin has such a long name
list of his friends, and he would like to send a greeting message
to each of them. What's worse, Merlin has another long name list of
senders that have sent message to him, and he doesn't want to send
another message to bother them Merlin is so polite that he always
replies each message he receives immediately). So, before he begins
to send message, he needs to figure to how many friends are left to
be sent. Please write a program to help him. Here is something that
you should note. First, Merlin's friend list is not ordered, and
each name is alphabetic strings and case insensitive. These names
are guaranteed to be not duplicated. Second, some senders may send
more than one message to Merlin, therefore the sender list may be
duplicated. Third, Merlin is known by so many people, that's why
some message senders are even not included in his friend
list.

输入

There are multiple test cases. In each case, at the first line
there are two numbers n and m
(1<=n,m<=20000), which is the number
of friends and the number of messages he has received. And then
there are n lines of alphabetic strings(the length of each will be
less than 10), indicating the names of Merlin's friends, one per
line. After that there are m lines of alphabetic strings, which are
the names of message senders. The input is terminated by n=0.

输出

For each case, print one integer in one line which indicates the
number of left friends he must send.

示例输入

5 3 

Inkfish 

Henry 

Carp 

Max 

Jericho 

Carp 

Max 

Carp 

0

示例输出

3

认真理解题意