In the land of Eden, all phone conversations are happy ones. People complaining on the phone are immediately put in jail. To enforce this law, the police taps all phone conversations.
The police wants to hire the approriate number of operators to listen to all conversations in a given period of time. Unfortunately, each of their operators can listen to one conversation only before needing a really long break to rest from the effort.
As a contractor of the police department, you have been asked to provide a program capable of determining the required number of operators. If the program does not work correctly, you will be put in jail as well, along with all the unhappy complainers. Do you really want to end up there?