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: When Mike was in college he had a huge crush on this girl. Sentence2: He thought they would be perfect together. Sentence3: So he decided to ask her out. Sentence4: He was pretty upset to find out she had a bf and was a huge smoker. Sentence5: He just found that to be a really unhealthy habit and moved on.
Bf, Mike, Girl