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问题 B: 连环杀手

内存限制：256 MB 时间限制：2 S
题面：传统 评测方式：文本比较 上传者：
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题目描述

我们敬爱的侦探Sherlock目前正试图抓住一个每天都要杀一个人的连环杀手。利用他的推理能力，他了解到凶手有一个选择下一个受害者的策略。
凶手在第一天开始有两个潜在的受害者，从这两个人中选择一个，杀死选定的受害者，然后用一个新的人取代他。他每天都会重复这个程序。这样一来，每天他都有两个潜在的受害者可以选择。Sherlock知道最初的两个潜在受害者。另外，他还知道某一天发生的谋杀案以及取代这个受害者的新人。
你需要帮助他在每一天得到所有成对的潜在受害者，这样Sherlock就能观察到一些规律。


Our beloved detective, Sherlock is currently trying to catch a serial killer who kills a person each day. Using his powers of deduction, he came to know that the killer has a strategy for selecting his next victim.
The killer starts with two potential victims on his first day, selects one of these two, kills selected victim and replaces him with a new person. He repeats this procedure each day. This way, each day he has two potential victims to choose from. Sherlock knows the initial two potential victims. Also, he knows the murder that happened on a particular day and the new person who replaced this victim.
You need to help him get all the pairs of potential victims at each day so that Sherlock can observe some pattern.
Input
First line of input contains two names (length of each of them doesn't exceed 10), the two initials potential victims. Next line contains integer n (1≤n≤1000), the number of days.
Next n lines contains two names (length of each of them doesn't exceed 10), first being the person murdered on this day and the second being the one who replaced that person.
The input format is consistent, that is, a person murdered is guaranteed to be from the two potential victims at that time. Also, all the names are guaranteed to be distinct and consists of lowercase English letters.
Output
Output n+1 lines, the i-th line should contain the two persons from which the killer selects for the i-th murder. The (n+1)-th line should contain the two persons from which the next victim is selected. In each line, the two names can be printed in any order.
Examples
Input 
ross rachel
4
ross joey
rachel phoebe
phoebe monica
monica chandler
Output 
ross rachel
joey rachel
joey phoebe
joey monica
joey chandler
Input 
icm codeforces
1
codeforces technex
Output 
icm codeforces
icm technex
Note
In first example, the killer starts with ross and rachel.
  • After day 1, ross is killed and joey appears.
  • After day 2, rachel is killed and phoebe appears.
  • After day 3, phoebe is killed and monica appears.
  • After day 4, monica is killed and chandler appears.

输入格式

输入的第一行包含两个名字（每个名字的长度不超过10），两个潜在受害者的首字母。下一行包含整数n（1≤n≤1000），代表天数。
接下来的n行包含两个名字（每个名字的长度不超过10），第一个是在这一天被谋杀的人，第二个是替代这个人的人。
输入的格式是一致的，也就是说，一个被谋杀的人保证是来自当时的两个潜在受害者。另外，所有的名字都保证是不同的，并且由小写英文字母组成。

输出格式

输出n+1行，第i行应包含凶手从中选择的第i次谋杀的两个人。第(n+1)行应该包含下一个受害者所选择的两个人。在每一行中，这两个人的名字可以按任何顺序打印。

输入样例 复制 

ross rachel
4
ross joey
rachel phoebe
phoebe monica
monica chandler

输出样例 复制 

ross rachel
joey rachel
joey phoebe
joey monica
joey chandler

数据范围与提示

在第一个样例中，凶手从ross和rachel开始。

    第1天后，ross被杀，joey出现。
    第2天后，rachel被杀，phoebe出现。
    第3天后，phoebe被杀，monica出现。
    第4天后，monica被杀，chandler出现。

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