You are facing six conveyor belts which are transporting cakes from the left side of the screen in your direction. You have to catch the cakes when they reach the end of their line and prevent them from dropping on the floor. Since the conveyor belts run at different speeds it sometimes happens that two cakes reach the end of their respective lines at the same time. So that you will not drop one of the two cakes you can push a button which will halt the conveyor belt of your choice for four seconds so that you can take of each cake one at a time.
