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.
Q: Sentence1: Kay built himself a raft. Sentence2: He used planks of scrap wood, and nails. Sentence3: He worked hard on it all spring. Sentence4: Kay's raft floated.
A:

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
4, Come summer, he tested it out in the lake.