Definition: 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.
Input: Sentence1: The professor gave everyone a final exam. Sentence2: The next day, he expressed his frustration by yelling at the class. Sentence3: He said that 95% of the class failed. Sentence4: We tried to argue about how unfair the test is. Sentence5: After several discussions, he decided to give test retakes.
Output:
Professor