class Shape:
    def area(self):
        return 0
class Circle(Shape):
    def __init__(self, radius):
        self.radius = radius

    def area(self):
        return math.pi * self.radius * self.radius
class Square(Shape):
    def __init__(self, side):
        self.side = side

    def area(self):
        return self.side * self.side
    
r=float(input("请输入半径r:"))
side=float(input("请输入边长side："))
shapes=[Circle(r),Square(side)]
for i in shapes:
    print(i.__class__.__name__,"面积为：",i.area())