Once upon a time, there lived a rich man. He had a servant (仆人). He and the servant(仆人） loved wine and good food very much. Each time the rich man left his home, the servant would drink the wine and eat up all the nice food in the house. The rich man knew what his servant did, but he had never caught his servant doing that.
One morning, when he left home, he said to the servant, “Here are two bottles of poison (毒药) and some nice food in the house. You must take good care of them.” With these words, he went out.
But the servant knew that the rich man had said was untrue. After the rich man was away from his home, he enjoyed a nice meal. Because he drank too much, he was drunk and fell to the ground. When the rich man came back, he couldn't find his food and his wine. He became very angry. He woke the servant up. But the servant told his story very well. He said a cat had eaten up everything. He was afraid to be punished, so he drank the poison to kill himself.
，过点
的直线交抛物线于点M、N，交y轴于点P，若
，则
（ ）
