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: Sam wanted to bake a cake for his friend's birthday. Sentence2: He checked his ingredients and saw he had no milk. Sentence3: Sam decided to just use water instead. Sentence4: When the cake was finished he presented it to his friend. Sentence5: She said it looked good and tasted okay.
Friend, Sam