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.

Example Input: Sentence1: My dog died last year from old age. Sentence2: He was buried under a huge pink rose bush. Sentence3: We buried him inside his favorite carrier, a red one. Sentence4: We placed a professionally made stone on his grave. Sentence5: The inscription said he was a dog with the heart of a lion.
Example Output: I (myself), Dog

Example Input: Sentence1: Maggie's 60th Birthday is approaching. Sentence2: She is fearful of growing old. Sentence3: Watching a commercial she sees an anti-aging cream. Sentence4: Maggie reaches into her purse for her credit card. Sentence5: She purchases the cream as a birthday gift to herself.
Example Output: Maggie

Example Input: Sentence1: Pete had been looking forward to building a treehouse for years. Sentence2: When his son Seth turned 8, he decided they could build one together. Sentence3: Pete gathered all the wood and materials, and was excited to start. Sentence4: But 10 minutes into building, Seth wandered off to play video games. Sentence5: He realized his son didn't care about the project as much as he did.
Example Output:
Pete, Seth