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.
Input: Sentence1: Ana had a math test. Sentence2: But she had not studied. Sentence3: She decided to copy her partner's paper. Sentence4: Luckily, she was not caught. Sentence5: She scored a B on the test by cheating.
Output:
Partner, Ana