Task: Question Understanding
Input (English): Passage: Lions quarterback Matthew Stafford threw four interceptions, as Tampa Bay upset Detroit 24-21. The Buccaneers became the first team since 1978 to start the season 0-8 and win their next three games. Stafford was leading the Lions on a potential game-winning or game-tying drive in the final minute. At the Tampa Bay 28 yard line with 1:00 left, Stafford threw to Calvin Johnson at the 3 yard line. Johnson appeared to catch the ball, but it was stripped out and fell into the hands of Johnthan Banks for an interception, and sealed the win for Tampa Bay.
Question: By how many points were the Detroit Lions upset by?
Output (English): number