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: Trey was very ill. Sentence 2: His doctor couldn't figure out what the problem was. Sentence 3: He ran a lot of tests. Sentence 4: Finally, the doctor solved the mystery. Sentence 5: It had been the hardest case he'd ever had.

The Doctor