MAYBE

'Pop* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  a__f(a(), b(), X) -> a__f(X, X, mark(X))
     , a__c() -> a()
     , a__c() -> b()
     , mark(f(X1, X2, X3)) -> a__f(X1, X2, mark(X3))
     , mark(c()) -> a__c()
     , mark(a()) -> a()
     , mark(b()) -> b()
     , a__f(X1, X2, X3) -> f(X1, X2, X3)
     , a__c() -> c()}

Proof Output:    
  The input cannot be shown compatible
The following warning(s) occured:

 Warning when parsing problem:
   Unsupported strategy 'OUTERMOST'