class Screen(object):
    @property
    def width(self):
        return self._width

    @width.setter
    def width(self, w):
        if not isinstance(w, int):
            raise TypeError("width must be integer!")
        if 0 > w:
            raise Exception("width must bigger than 0!")
        self._width = w

    @property
    def height(self):
        return self._height

    @height.setter
    def height(self, h):
        if not isinstance(h, int):
            raise TypeError("height must be integer!")
        if 0 > h:
            raise Exception("height must bigger than 0!")
        self._height = h

    @property
    def resolution(self):
        return self._width * self._height