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: Carla wanted to be more active. Sentence2: Her friend suggest she start biking with her at the local park. Sentence3: Carla went to the store to buy a bike. Sentence4: She found a bike she liked and bought it. Sentence5: Carla began riding with her friend that day.
Output:
Carla, Friend