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: Lily was looking forward to her birthday - she always had a big party. Sentence2: But her best friend wasn't mentioning any plans. Sentence3: On her birthday, she still hadn't heard anything about a celebration. Sentence4: Lily was very disappointed when she walked into her dark living room.

Her mood changed quickly when her friends jumped out to surprise her.