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: Bill wanted to ask out John but Bill was shy. Sentence2: John knew that Bill liked him so he asked him out instead. Sentence3: Bill was happy that John asked him out and so he agreed. Sentence4: Bill and John went on their first date and it was fantastic. Sentence5: Bill and John decided to get married a year later.
Output:
John, Bill