Given a set of banned words `S`, please find out whether it is possible to construct a string `str _{1..∞}` with infinite length that fulfills the following constrains:

- It consists of only the first
`M`types of lowercase letters in the alphabet. For example`M`= 3, only 'a', 'b' and 'c' are allowed to appear in the string. - There does not exist such (
`i`,`j`) that`str`is a banned word in_{i..j}`S`(1 <=`i`<=`j`< ∞). - There does not exist such (
`i`,`j`) that for any`k`>=`i`,`str`=_{k}`str`(1 <=_{(j + k)}`i`,`j`< ∞).

There are multiple test cases. The first line of input contains an integer `T` indicating the number of test cases. For each test case:

The first line contains two integers `N` (1 <= `N` <= 100) and `M` (1 <= `M` <= 26). The following `N` lines, each line contains contains a non-empty string indicating a banned word in `S`. The length of each word will not exceed 1000 and the word only consists of lowercase letters.

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