Most Frequent Hashtag

You are given a list of social media posts. Each post is a string that may contain one or more hashtags. A hashtag is defined as a contiguous sequence of word characters (letters, digits, and underscores) that starts with the symbol #.

Your task is to determine the most frequently occurring hashtag across all posts. In the case of a tie, return the hashtag that appears first in the order of occurrence in the input.

In mathematical terms, if we denote the number of occurrences of a hashtag \( h \) by \( f(h) \), then you are to find a hashtag \( h^* \) satisfying \[ h^* = \min \{ h : f(h) = \max_{h'} f(h') \} \text{ (in order of first occurrence)} \]

If there are no hashtags in any of the posts, output None.

inputFormat

The first line contains an integer n indicating the number of posts. Each of the following n lines contains a post (a non-empty string).

outputFormat

Output a single line containing the most frequent hashtag. If no hashtag is found in any post, output None.

## sample

4
#life is beautiful #happy
Enjoying #life #happy times
Just a random post
#happy vibes

#happy

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