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: Betty's friend was very thoughtful and often sent her gifts. Sentence2: One time she sent her flower bulbs to grow indoors. Sentence3: Betty planted her bulbs and was excited to see what they'd look like. Sentence4: They bloomed into beautiful flowers, but smelled sickeningly sweet. Sentence5: Betty couldn't tolerate the smell and had to toss the flowers outside.
Output:
Betty, Betty's friend