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: I am Chinese. Sentence2: One day I was sitting on the bench in front of my building. Sentence3: A young man came by and said I looked like his father. Sentence4: He was white, however, as was his father. Sentence5: He said I just looked like his dad.
Example Output: I (myself), Young man

Example Input: Sentence1: Felix was highly interested in life in the colonial United States. Sentence2: He loved going to reenactments and colonial fairs. Sentence3: He studied their ways of making goods and doing services. Sentence4: Eventually he found employment in colonial Williamsburg. Sentence5: It was a good educational opportunity, and a chance to share his love.
Example Output: Colonial williamsburg, Felix, Colonial united states

Example Input: Sentence1: An asteroid blazed across the sky. Sentence2: It fell to the ground with a soft shock. Sentence3: A man walked by and looked at it. Sentence4: The rock glowed with heat as he reached for it. Sentence5: The man felt the heat and back off until it was cool.
Example Output:
A man

