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.
Q: Sentence1: Fred put in his headphones and listened to music. Sentence2: He sang along to the music as he went about his day. Sentence3: A person on the street stopped Fred to ask about his singing. Sentence4: He wanted to know what song he was singing to. Sentence5: Fred sang the name of the song to the man and walked on.
A:
Person, Fred