A small stream has seven equidistant stones in line from one bank to the other. Three black and three white frogs on either side are sitting on the three nearest stones to their respective banks like so: B B B _ W W W with one stone unoccupied in the middle. Can you help both group of frogs to cross to the other side if (a) A frog can only shift to a stone ahead of it or can jump over an opposite colour frog; (b) No frog can move backward or into the water and one stone cannot accommodate more than one frog at a time. The real challenge however is: can you device a strategy for m black and n white frogs (with the assumption that there are m + n + 1 stones laid across) in a similar situation? Can you also come up with a formula for minimum no of steps required?