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.

[EX Q]: Sentence1: Ella wrote her grandma a letter. Sentence2: She went to the post office to mail it. Sentence3: But they told her she needed a stamp! Sentence4: A kind stranger gave little Ella the stamp. Sentence5: Ella happily posted her letter.
[EX A]: Ella, Stranger, Grandma

[EX Q]: Sentence1: Sean was in a bad mood. Sentence2: And he realized that his room was a mess. Sentence3: He decided to clean up and organize everything. Sentence4: And his room looked beautiful. Sentence5: And Sean was in a bad mood less often.
[EX A]: Sean

[EX Q]: Sentence1: I've been getting exceptionally good at a particular game. Sentence2: The game is notoriously difficult. Sentence3: I am the only one of my friends to reach the final challenge round. Sentence4: Unfortunately I can not yet beat that final challenge round. Sentence5: But I intend to play the game all weekend until I beat it.
[EX A]:
I (myself)