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: Rex hasn't left his tiny apartment all day. Sentence2: Finally he decides to meet a friend for coffee. Sentence3: They each have a coffee at the local coffee shop. Sentence4: As Rex walks home, he realizes that the coffee will keep him awake. Sentence5: Still he is glad that he left his apartment to see a friend.
Rex, A friend