Detailed Instructions: In this task, you're given four sentences of a story written in natural language in which one part is missing. Your job is to predict the position and missing part of the story and return in the following format: position, missing part. The missing part is a sentence that completes the story, and the position is the number of the missing sentence in the new story.
Problem:Sentence1: In the lift line, we started talking to another couple. Sentence2: We found out that they were celebrating the wife's birthday. Sentence3: The four of us had drinks in the lodge that night. Sentence4: We had our first swingers experience that night.
Solution:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
1, We went snow skiing for my wife's birthday.