Instructions: In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.
Input: Sentence1: Rick played video games for over 15 Year's. Sentence2: However, he was starting to get bored of them. Sentence3: He decided to a pick up a game called Halo 5. Sentence4: He didn't think too much about it. Sentence5: However, Halo 5 ended up being his favorite game.
Output:
Rick