1. Move Thread 0 to end. 2. do a few iterations through thread 1 (e.g. n=5) 3. step darkness++ concurrently (via expand), so that darkness=1 4. step thread 0

1. Move Thread 0 to end. 2. do a few iterations through thread 1 (e.g. n=5) 3. step darkness++ concurrently (via expand), so that darkness=1 4. step thread 0 to Monitor.Wait(sanctum) 5. the rest is straightforward.