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.
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Question: Sentence1: Mark was a big fan of nature. Sentence2: He decided to bring trees to the city. Sentence3: He would take a truck load of trees down each week. Sentence4: He would then plant the trees in parks. Sentence5: Over time the trees grew and now Mark is happy!

Answer: Mark

Question: Sentence1: While he was swimming one day, Jim saw something in the water. Sentence2: He wasn't sure what it was, but he knew it didn't belong. Sentence3: He dove underneath the surface. Sentence4: He pulled the object up to the surface. Sentence5: Jim discovered that the object was a bag of rubber clown noses.

Answer: Jim

Question: Sentence1: Henry was tired. Sentence2: But he had to finish his homework. Sentence3: He stayed up until 4 AM to finish it. Sentence4: But the next day, his teacher forgot to collect it. Sentence5: And Henry did not want to upset the class by reminding her.

Answer:
Teacher, Henry's class, Henry