Definition: 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: Tom got a call from the library. Sentence2: They told him he needed to return a book. Sentence3: Tom forgot he still had it. Sentence4: He looked in several places to find it. Sentence5: He eventually found it and returned it.
Output:
Tom