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: Consider Input: Sentence1: She opened the back door and propped it. Sentence2: The dog didn't notice. Sentence3: A loud noise got her attention. Sentence4: It was a bird in the backyard. Sentence5: She ran outside to check it out.

Output: Dog, Bird

Input: Consider Input: Sentence1: Rachel was riding her new bike for the first time. Sentence2: She was excited to try it. Sentence3: She took off the training wheels and hopped on. Sentence4: As she got on, she immediately lost balance and fell. Sentence5: She scraped her knee but thankfully it was benign.

Output: Rachel

Input: Consider Input: Sentence1: Linda was having stomach pain and cramps. Sentence2: But changing her diet didn't help very much. Sentence3: She read about the benefits of fasting. Sentence4: So she went for long periods of time without eating. Sentence5: By letting her digestive system rest, Linda's stomach issues improved.
Output: Linda