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: Fred's son had a baseball game today. Sentence2: He promised him he would be there. Sentence3: But at the end of the day Fred never came. Sentence4: His son was so upset and had been looking forward to him. Sentence5: Fred was simply stuck in bad traffic and it was impossible to come.
Output:
Fred, Fred's son