Definition: In this task, you're given five sentences, numbered 1 through 5. Your job is to generate a title for the story that makes complete sense. The title must be short, with less than three words, use simple language, and include the main topic of the story.
Input: Sentence 1: Frank was gifted a puzzle for Christmas. Sentence 2: After a long week of work, he decided to solve it over the weekend. Sentence 3: The puzzle was actually pretty difficult. Sentence 4: But Frank nearly finished the puzzle in a few hours. Sentence 5: Turns out the puzzle was missing a piece!

Puzzle