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: Callie was out with friends for dinner. Sentence2: Her waiter hadn't been around to take their orders. Sentence3: Callie and her friends had to place their orders with another waiter. Sentence4: She saw their waiter leaning on the bar, playing on his phone. Sentence5: Callie didn't leave the waiter a tip.
Callie, Waiter, Another waiter, Friends