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: Tina had sampled her mom's wine last night. Sentence2: Her mom had caught her and grounded her. Sentence3: But the next morning, Tina woke with a terrible hangover. Sentence4: She thought that was a far worse punishment than the grounding. Sentence5: Tina vowed never to drink alcohol again!
Example Output: Tina, Her mom

Example Input: Sentence1: When the little boy went home, he couldn't find his mother or father. Sentence2: He looked all around. Sentence3: He called their names but no one answered. Sentence4: Eventually a neighbor heard him. Sentence5: She said his parents were at her home.
Example Output: Mother, Father, Neighbor, The little boy

Example Input: Sentence1: Alex's son begged him to go hiking with a group of Alex's friends. Sentence2: Alex was concerned as his son was only 3. Sentence3: But Alex's friends promised to look after him. Sentence4: On the trail, the friends got too caught up in their conversation. Sentence5: Alex's son vanished and no one knew how.
Example Output:
Friends, Son, Alex