Instructions: 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: Ken went to buy groceries. Sentence2: He noticed they had cheap bags for sale. Sentence3: He figured he would buy one instead of using disposable. Sentence4: Ken was able to get all his groceries in it. Sentence5: He has used it several times.
Output:
Ken