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.
Q: Sentence1: Bobby was a little boy, whose favourite toy was a bear. Sentence2: The bear's name was also Bobby, and he carried him everywhere. Sentence3: One day, he dropped Bobby in the park and a dog stole it. Sentence4: His mum didn't see this happen and they left without the bear. Sentence5: The next day, Bobby found his bear freshly washed, sat on the see-saw.
A:
Mum, Dog, Bobby