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: Marcus was playing his guitar at school. Sentence2: His friend Matthew approached him and asked about the music. Sentence3: Soon they were in a heated conversation about their music tastes. Sentence4: The duo decided that they should collaborate on some music. Sentence5: The resulting album was very popular with all of their friends.
A:
Marcus, Their friends, Matthew