P6873 [COCI 2013/2014 #6] FONT

We define a test sentence as a string that contains all lowercase English letters. Now you are given $N$ words. Find the maximum number of test sentences that can be formed from these words. Each word can be used at most once in a test sentence, and the order of words in the sentence does not matter, i.e., `uvijek jedem sarmu` and `jedem sarmu uvijek` are considered the same.

The first line contains an integer $N$, the number of words. The next $N$ lines each contain one word, with length not exceeding $100$. It is guaranteed that all words are distinct.

Output the maximum number of test sentences that can be formed.

#### Constraints $1\le N\le 25$. #### Sample Explanation #### Explanation for Sample 1 All words except `a` must be used in the test sentence, because each of them contains a letter that cannot be found in any other word. Therefore, there are two possible ways. The first is the sentence containing all words, and the second is the sentence formed by all words except `a`. #### Explanation for Sample 3 This sample consists of consecutive lowercase English letters. #### Notes **This problem is translated from [COCI2013-2014](https://hsin.hr/coci/archive/2013_2014/) [CONTEST #6](https://hsin.hr/coci/archive/2013_2014/contest6_tasks.pdf) _T2 FONT._** Translated by ChatGPT 5