Detailed 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.
Problem:Sentence1: John went to live in Europe for a year. Sentence2: Every Sunday night the phone would ring in the middle of the night. Sentence3: He'd answer with a sleepy voice. Sentence4: And his mother would ask him how he was doing. Sentence5: He'd explain that there was a time difference but to no avail.
Solution:
John, Mother