Maximum Compatible Spells

You are given an integer n representing the number of spells and n strings where each string represents a spell. Two spells are considered compatible if they do not share any common character, i.e., if for two spells S₁ and S₂ we have \(S_1 \cap S_2 = \emptyset\). Your task is to select a subset of spells such that every pair of spells in the subset is compatible, and the number of spells chosen is maximized.

Input Format: The input begins with an integer n on the first line, followed by n lines each containing a spell (a string of lowercase letters).

Output Format: Output a single integer representing the maximum number of pairwise compatible spells.

Example:

Input:
4
abc
def
gh
cz
Output:
3

</p>

inputFormat

The first line of input is an integer n representing the number of spells. The next n lines each contain a non-empty string representing a spell.

outputFormat

Print a single integer representing the maximum number of spells that can be selected such that no two spells share any common characters.

## sample

4
abc
def
gh
cz

3