MAYBE
* Step 1: Failure MAYBE
  + Considered Problem:
      - Strict TRS:
          f(0(),y,0(),u) -> true()
          f(0(),y,s(z),u) -> false()
          f(s(x),0(),z,u) -> f(x,u,minus(z,s(x)),u)
          f(s(x),s(y),z,u) -> if(le(x,y),f(s(x),minus(y,x),z,u),f(x,u,z,u))
          perfectp(0()) -> false()
          perfectp(s(x)) -> f(x,s(0()),s(x),s(x))
      - Signature:
          {f/4,perfectp/1} / {0/0,false/0,if/3,le/2,minus/2,s/1,true/0}
      - Obligation:
          innermost runtime complexity wrt. defined symbols {f,perfectp} and constructors {0,false,if,le,minus,s,true}
  + Applied Processor:
      Ara {heuristics_ = NoHeuristics, minDegree = 1, maxDegree = 3, araTimeout = 60, araFindStrictRules = Nothing, araSmtSolver = MiniSMT}
  + Details:
      The input can not be schown compatible.
MAYBE