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.

Sentence1: Bill and Amy dated for four years. Sentence2: They finally decided to get engaged. Sentence3: Bill's father disapproved of the impending marriage. Sentence4: This put a strain on Bill's relationship with his father. Sentence5: After the wedding things were never the same between Bill and his dad.
Amy, Bill, Father