MAYBE

We are left with following problem, upon which TcT provides the
certificate MAYBE.

Strict Trs:
  { ackin(s(X), s(Y)) -> u21(ackin(s(X), Y), X)
  , u21(ackout(X), Y) -> u22(ackin(Y, X)) }
Obligation:
  innermost runtime complexity
Answer:
  MAYBE

The input cannot be shown compatible

Arrrr..