MAYBE

'epo* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  ackin(s(X), s(Y)) -> u21(ackin(s(X), Y), X)
     , u21(ackout(X), Y) -> u22(ackin(Y, X))}

Proof Output:    
  The input cannot be shown compatible