This is a famous question that I heard from one of my friends.
There is a set of monks who is meditating. All of them get together to a certain location daily and meet each other but they are not talking with each other and no any other communication used but thinking power of every monk is at the same level. One day a god came to them and told them a fixed number of people will sick tomorrow. Every monk who is sick has a red spot on their forehead and anyone can see this red spot except himself(if you are infected you can't see your red spot but can see others ones). When monks get together the monks who have been infected will realize they have the illness and will not participate to the meeting the next day onward. The god know 10 monks will get sick at this time and so us(The problem solvers but monks don't know the count is 10 but monks know that is a fixed number )..;)
The question is that
How many number of days it will take not to come to the meeting for monks who has the illness from the day they became ill?
I heard this problem from darshana