Detailed Instructions: 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.
Q: Sentence1: Dan had a dead Aspen tree along his walkway. Sentence2: He got out his chainsaw and cut it down. Sentence3: Dan bucked the tree into fireplace sized pieces. Sentence4: When it got cold he used them to heat his house. Sentence5: Dan was sad about losing the tree but happy to be warm.
A:
Dan