WORST_CASE(?,O(n^1))

Solution:
---------

  0 :: [] -(0)-> A(1)
  0 :: [] -(0)-> A(15)
  0 :: [] -(0)-> A(11)
  0 :: [] -(0)-> A(7)
  S :: [A(1)] -(1)-> A(1)
  S :: [A(15)] -(15)-> A(15)
  S :: [A(2)] -(2)-> A(2)
  dbl :: [A(1) x A(15)] -(8)-> A(1)
  unsafe :: [A(15)] -(7)-> A(1)


Cost Free Signatures:
---------------------

  0 :: [] -(0)-> A_cf(0)
  S :: [A_cf(0)] -(0)-> A_cf(0)
  dbl :: [A_cf(0) x A_cf(0)] -(0)-> A_cf(0)
  unsafe :: [A_cf(0)] -(0)-> A_cf(0)


Base Constructors:
------------------
  0_A :: [] -(0)-> A(1)
  S_A :: [A(1)] -(1)-> A(1)