|시간 제한||메모리 제한||제출||정답||맞은 사람||정답 비율|
|1 초||512 MB||3||3||3||100.000%|
You are given $n$ strings, each a permutation of the first $k$ upper-case letters of the alphabet.
String $s$ is a subsequence of string $t$ if and only if it is possible to delete some (possibly zero) characters from the string $t$ to get the string $s$.
Compute the length of the longest common subsequence of all $n$ strings.
The first line of input contains two integers $n$ ($1 \le n \le 10^5$) and $k$ ($1 \le k \le 26$), where $n$ is the number of strings, and the strings are all permutations of the first $k$ upper-case letters of the alphabet.
Each of the next $n$ lines contains a single string $t$. It is guaranteed that every $t$ contains each of the first $k$ upper-case letters of the alphabet exactly once.
Output a single integer, the length of the longest subsequence that appears in all $n$ strings.
2 3 BAC ABC
3 8 HGBDFCAE ADBGHFCE HCFGBDAE
6 8 AHFBGDCE FABGCEHD AHDGFBCE DABHGCFE ABCHFEDG DGABHFCE