重点单词：

parse v/n.分析，研究；

palindrome n.回文；

concatenate v.链接，连接，adj.连接的，连续的；

peculiar adj.奇怪的，特别的，不寻常的；

subsequence n.随后，接着；

a subsequence of n.一系列；

出处：https://acs.jxnu.edu.cn/contest/23/board/challenge/F

Peculiar Movie Preferences

独特的电影偏好

描述：

Mihai plans to watch a movie. He only likes palindromic movies, so he wants to skip some (possibly zero) scenes to make the remaining parts of the movie palindromic.

米海计划看一部电影。他只喜欢回文电影，所以他想跳过一些（可能零）场景，使电影的其余部分回文。

You are given a list s">ss of n">nn non-empty strings of length at most 3">33, representing the scenes of Mihai's movie.

s">n">3">你会得到一个由n个长度不超过3的非空字符串组成的列表，代表米海电影的场景。

A subsequence of s">s is called awesome if it is non-empty and the concatenation of the strings in the subsequence, in order, is a palindrome.

s">某一系列情景s会被称作绝妙如果他是非空的，且在这一系列中连续的字符串是按照一定规律回文；

Can you help Mihai check if there is at least one awesome subsequence of s">ss?

A palindrome is a string that reads the same backward as forward, for example strings "z", "aaa", "aba", "abccba" are palindromes, but strings "codeforces", "reality", "ab" are not.

A sequence a">aa is a non-empty subsequence of a non-empty sequence b">bb if a">aa can be obtained from b">bb by deletion of several (possibly zero, but not all) elements.

你能帮Mihai看看是否有至少一个很棒的s子序列吗？

回文是一个前后读相同的字符串，例如字符串“z”、“aaa”、“aba”、“abccba”是回文，而字符串“codeforces”、“reality”、“ab”则不是。

如果可以通过删除几个（可能是零，但不是全部）元素从b中获得A，则序列A是非空序列b的非空子序列。

输入：

The first line of the input contains a single integer t">tt (1≤t≤100">1≤t≤1001≤t≤100) — the number of test cases. The description of test cases follows.

The first line of each test case contains a single integer n">nn (1≤n≤105">1≤n≤1051≤n≤105) — the number of scenes in the movie.

Then follows n">nn lines, the i">ii-th of which containing a single non-empty string si">sisi of length at most 3">33, consisting of lowercase Latin letters.

It is guaranteed that the sum of n">nn over all test cases does not exceed 105">105105.

输入的第一行包含一个整数t（1≤T≤100）-测试用例的数量。测试用例的描述如下。

每个测试用例的第一行包含一个整数n（1）≤N≤105）-电影中的场景数量。

然后是n行，第i行包含一个长度不超过3的非空字符串si，由小写拉丁字母组成。

保证所有测试用例中n的总和不超过105。

输出：

For each test case, print "YES" if there is an awesome subsequence of s">ss, or "NO" otherwise (case insensitive).

样例输入：

6
5
zx
ab
cc
zx
ba
2
ab
bad
4
co
def
orc
es
3
a
b
c
3
ab
cd
cba
2
ab
ab

样例输出：

YES
NO
NO
YES
YES
NO

注释：

In the first test case, an awesome subsequence of s">ss is [ab,cc,ba]">[ab,cc,ba]