CF1628B.Peculiar Movie Preferences

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.

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

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

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

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

米海计划观看一部电影。他只喜欢回文电影，因此他希望跳过一些（可能为零）场景，使得电影剩余部分构成回文。

你将得到一个包含 $n$ 个非空字符串的列表 $s$，每个字符串长度至多为 $3$，代表米海这部电影的各个场景。

若一个 $s$ 的子序列满足：非空，且其中各字符串按顺序拼接后构成回文，则称该子序列为“极好的”（awesome）。

你能帮米海判断 $s$ 中是否至少存在一个“极好的”子序列吗？

回文是指正读与反读都相同的字符串，例如字符串 "z"、"aaa"、"aba"、"abccba" 都是回文，但字符串 "codeforces"、"reality"、"ab" 不是回文。

若序列 $a$ 可通过从非空序列 $b$ 中删除若干（可能为零个，但不能全部）元素而得到，则称 $a$ 是 $b$ 的一个非空子序列。

The first line of the input contains a single integer $t$ ($1 \le t \le 100$) — the number of test cases. The description of test cases follows.

The first line of each test case contains a single integer $n$ ($1 \le n \le 10^5$) — the number of scenes in the movie.

Then follows $n$ lines, the $i$-th of which containing a single non-empty string $s_i$ of length at most $3$, consisting of lowercase Latin letters.

It is guaranteed that the sum of $n$ over all test cases does not exceed $10^5$.

输入的第一行包含一个整数 $t$（$1 \le t \le 100$），表示测试用例的数量。随后是各测试用例的描述。

每个测试用例的第一行包含一个整数 $n$（$1 \le n \le 10^5$），表示电影中的场景数量。

接下来是 $n$ 行，其中第 $i$ 行包含一个长度至多为 $3$ 的非空字符串 $s_i$，该字符串仅由小写拉丁字母组成。

保证所有测试用例的 $n$ 值之和不超过 $10^5$。

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

对于每个测试用例，如果字符串 $s$ 存在“极好”子序列，则输出 "YES"；否则输出 "NO"（不区分大小写）。

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

在第一个测试用例中，字符串 $s$ 的一个极好子序列是 $[ab, cc, ba]$