P3419 [POI2005]SAM-Toy Cars[贪心好题]
题目描述 Johnny is a little boy - he is only three years old and enjoys playing with toy cars very much. Johnny has nnn different cars. They are kept on a shelf so high, that Johnny cannot reach it by himself. As there is little space in his room, at no moment may there be more than kkk toy cars on the floor. Johnny plays with one of the cars on the floor. Johnny's mother remains in the room with her son all the time. When Johnny wants to play with another car that is on the floor, he reaches it by himself. But when the toy is on the shelf, his mummy has to hand it to him. When she gives Johnny