class Shape:
    def area(self):
        return 0

class Circle(Shape):
    def __init__(self, r):
        self.r = r
    def area(self):
        return 3.14 * self.r * self.r
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())