MAYBE

'epo* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  f(a, empty()) -> g(a, empty())
     , f(a, cons(x, k)) -> f(cons(x, a), k)
     , g(empty(), d) -> d
     , g(cons(x, k), d) -> g(k, cons(x, d))}

Proof Output:    
  The input cannot be shown compatible