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: I was walking to my office complex. Sentence2: I noticed that all of the lights were off. Sentence3: I walked inside and I was confused because it was a workday. Sentence4: Suddenly, all of the lights turned on and confetti flew everywhere.

My coworkers through a surprise party for my birthday.