Q: 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.
Sentence1: Nathan dove into the pool. Sentence2: He over rotated his body during the dive. Sentence3: He hit the water on his back. Sentence4: The lifeguard heard the noise. Sentence5: The lifeguard jumped into the pool to help Nathan.
A:
Nathan, Lifeguard