Word Game

You are given a dictionary containing w words. Every dictionary word consists only of lowercase English letters from a to z, and each word has length at most 25.

You are also given a string S of length l. By removing some characters from S, the remaining characters can be written as a concatenation of words from the dictionary. Characters that are not removed must keep their original order.

Compute the minimum number of characters that must be removed from S so that the remaining string can be represented by dictionary words.

The first line contains w and l (1 <= w <= 600, 2 <= l <= 300).

The second line contains the string S.

Each of the next w lines contains one dictionary word.

Print the minimum number of characters that must be removed from S.

For browndcodw, removing the two d characters leaves browncow, which can be represented as the two dictionary words brown and cow.