class AAA a where
  (+++) :: a -> a -> a	    
  (///) :: a -> a -> a
  (***) :: Num a => a -> a -> a

  x *** y = x * x * y

instance AAA Double where
  x +++ y = 2*x + y
  x /// y = x/2 + y

instance AAA Integer where
  x +++ y = 10*x + y
  x /// y = x `div` y