class Point(object):
    """Represents a point in 2-D space."""

class Rectangle(object):
    """Represents a rectangle

    attributes: width, height, corner.
    """

    def __init__(self, x, y, width, height):
        pt = Point()
        pt.x = x
        pt.y = y
        self.width = width
        self.height = height
        self.corner = pt

    def __str__(self):
        return "(%.3f, %.3f, %.3f, %.3f)" % (
            self.corner.x, self.corner.y, self.width, self.height)

    def shift(self, dx, dy):
        self.corner.x += dx
        self.corner.y += dy

    def offset(self, dx, dy):
        x = self.corner.x + dx
        y = self.corner.y + dy
        return Rectangle(x, y, self.width, self.height)

    def __add__(self, other):
        x = min(self.corner.x, other.corner.x)
        y = min(self.corner.y, other.corner.y)
        mx = max(self.corner.x + self.width, other.corner.x + other.width)
        my = max(self.corner.y + self.height, other.corner.y + other.height)
        width = mx - x
        height = my - y
        return Rectangle(x, y, width, height)

r1 = Rectangle(10, 20, 10, 10)
r2 = Rectangle(20, 50, 15, 20)
print(r1 + r2)