class Quad
    def initialize(len_a, len_b, len_c, len_d)
        @len_a = len_a
        @len_b = len_b
        @len_c = len_c
        @len_d = len_d
    end

    def perimeter
        @len_a + @len_b + @len_c + @len_d
    end
end

class Rect < Quad
    def initialize (len_a, len_b)
        super(len_a, len_b, len_a, len_b)
    end

    def area
        @len_a * @len_b
    end
end

class Square < Rect
    def initialize(len)
        super(len, len)
    end

    def side_len
        @len_a
    end
end

class Trap < Quad
end

class Rhomb < Trap
    def initialize(len)
        super(len, len, len, len)
    end

    def side_len
        @len_a
    end
end



def test
    quad = Quad.new(5,10,49,22)
    rect = Rect.new(50, 10)
    squa = Square.new 10
    rhomb = Rhomb.new 15
    puts squa.is_a? Rect
    puts squa.is_a? Quad
    puts rhomb.is_a? Trap
    puts rhomb.is_a? Quad
    p "quad per = " + quad.perimeter.to_s
    p "squa per = " + squa.perimeter.to_s
    p "rhomb per = " + rhomb.perimeter.to_s
    p "rect area = " + rect.area.to_s
    p "squa per = " + squa.area.to_s
    p "squa side_len = " + squa.side_len.to_s
    p "rhomb side_len = " + rhomb.side_len.to_s

end

test