Given the task definition and input, reply with output. 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.

Sentence1: One day Ben was at the fair with his friends. Sentence2: They were having a good time there. Sentence3: One of ben's friends told him to play a game. Sentence4: Ben decided to give it a try. Sentence5: He shot the ball through the hook and won a bear for his friend.
Friends, Ben