AA - Longest Common Subsequence
题号：NC224697
时间限制：C/C++/Rust/Pascal 1秒，其他语言2秒
空间限制：C/C++/Rust/Pascal 256 M，其他语言512 M
64bit IO Format: %lld

题目描述

You are given  strings, each a permutation of the first  upper-case letters of the alphabet.
String  is a  of string  if and only if it is possible to delete some (possibly zero) characters from the string  to get the string .
Compute the length of the longest common  of all  strings.

输入描述:

The first line of input contains two integers  and , where  is the number of strings, and the strings are all permutations of the first  upper-case letters of the alphabet.
Each of the next  lines contains a single string . It is guaranteed that every  contains each of the first  upper-case letters of the alphabet exactly once.

输出描述:

Output a single integer, the length of the longest subsequence that appears in all  strings.
示例1

输入

复制 
2 3
BAC
ABC

输出

复制 
2
示例2

输入

复制 
3 8
HGBDFCAE
ADBGHFCE
HCFGBDAE

输出

复制 
3
示例3

输入

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6 8
AHFBGDCE
FABGCEHD
AHDGFBCE
DABHGCFE
ABCHFEDG
DGABHFCE

输出

复制 
4

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