Vasya writes his own library for building graphical user interface. Vasya called his creation VTK ( VasyaToolKit ). One of the interesting aspects of this library is that widgets are packed in each other. A widget is some element of graphical interface. Each widget has width and height, and occupies some rectangle on the screen. Any widget in Vasya's library is of type Widget . For simplicity we will identify the widget and its type. Types HBox and VBox are derivatives of type Widget , so they also are types Widget . Widgets HBox and VBox are special. They can store other widgets. Both those widgets can use the pack() method to pack directly in itself some other widget. Widgets of types HBox and VBox can store several other widgets, even several equal widgets — they will simply appear several times. As a result of using the method pack() only the link to the packed widget is saved, that is when the packed widget is changed, its image in the widget, into which it is packed, will also change. We shall assume that the widget a is packed in the widget b if there exists a chain of widgets a = c 1 , c 2 , ..., c k = b , k ≥ 2 , for which c i is packed directly to c i + 1 for any 1 ≤ i < k . In Vasya's library the situation when the widget a is packed in the widget a (that is, in itself) is not allowed. If you try to pack the widgets into each other in this manner immediately results in an error. Also, the widgets HBox and VBox have parameters border and spacing , which are determined by the methods set_border() and set_spacing() respectively. By default both of these options equal 0 . The picture above shows how the widgets are packed into HBox and VBox . At that HBox and VBox automatically change their size depending on the size of packed widgets. As for HBox and VBox , they only differ in that in HBox the widgets are packed horizontally and in VBox — vertically. The parameter spacing sets the distance between adjacent widgets, and border — a frame around all p