Last one for today. This is also probably the most difficult one.
You are the emperor of Medieval Japan and in 25 hours you must host a great banquet to honour a peace treaty between Japan and China. It is extremely important that everything goes as planned. You have 1000 bottles of wine you can use for the banquet, and tradition insists upon wine being served. But one of your spies tells you that exactly one of the bottles is poisoned.
The poison has no visual effects other than whoever drinks even the smallest amount will die in at least 20 hours.
You have over 1000 slaves at your disposal. You have a small number of prisoners also, some of whom are sentenced to be executed. However, you want to avoid killing innocent people wherever possible.
What is the smallest number of prisoners you must have drink from the bottles to deduce with absolute certainty which bottle is poisoned? Assuming you want to keep deaths to a minimum, in the worst case scenario, how many of these prisoners who test the wine will die?
Hint: