A person has one lion, one lamb and a bundle of grass. He wants to cross a river but there is only one boat and it can't sustain the weight of more than two articles at time. Also, he has to make sure that the lion doesn't eat the lamb and the lamb doesn't eat the grass. How will he get to the other side of the river with all three intact?
Take the lamb across, then the bundle of grass. Take the lamb back across and then take the lion across. Then take the lamb back across and they are all unharmed.