  A camel can carry one banana at a time on its back. It is on a diet and
therefore can only have one banana at a time in its stomach. As soon as it has
eaten a banana it walks a mile and then it needs a new banana (in order to be
able to continue its itinerary). Let there be a stock of N bananas at the
border of the desert. How far can the camel penetrate into the desert, starting
at this point? (Of course it can form new stocks with transported bananas.)
