He never found the PDF again. The server link was dead. The backup was gone. But sometimes, late at night, when he solved a difficult problem, he heard a faint hum from nowhere—and he knew Savchenko was still grading his work.

Not in sound. In understanding.

He turned the page. Problem 10.0: "You have learned to think like Savchenko. Now solve the final problem. What is the one question that destroys all others?"