At crazy hospital a doctor wanted to examine the crazies men to discover who will cure.So as to do this step ,he drew a door in a roof,then he asked them to open the door.Every on tried to open the door except one,the doctor thought that this crazy man who did not go to open the door he cured.In order to make sure,the doctor asked him:"why you did not go to open the door with your friends?"crazy man said:"because I have the key."