Definition: In this task, you're given a four sentences of story written in natural language. Your job is to complete end part of the story by predicting appropriate last sentence which is coherent with the given sentences.
Input: Sentence1: Frank filled up dozens of water balloons to throw at this sister. Sentence2: Little did he know she was ready for him. Sentence3: When he started the attack, she pulled out a huge water gun. Sentence4: It was much more effective than his balloons.

Frank bought a water gun the next day.