Definition: 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.
Input: Sentence1: I helped a customer today for nearly four hours. Sentence2: He was looking for the perfect engagement ring. Sentence3: I helped him pick a nice box and listened to what he was going to say. Sentence4: I rung him up and sent him on his way, happy to have helped. Sentence5: Only then did I realize I didn't put the ring in the box.
Output:
I (myself), Customer