A14806. 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.

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 $10^5$ .

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

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