Given the task definition and input, reply with output. 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: I had a contest with my friend at the beach. Sentence2: We wanted to see who could make the biggest sand castle. Sentence3: I was going to make mine huge. Sentence4: Unfortunately, it started to rain. Sentence5: We kicked over the castles and shook hands.
I (myself), Friend