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: Bill put a pot of oil on the range to heat up. Sentence2: He added kernels of popcorn. Sentence3: The popping started slowly then escalated. Sentence4: Soon the popcorn was raising the lid of the pot. Sentence5: He had put too much in so it was overflowing.
Bill