MAYBE

'Pop* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  isEmpty(cons(x, xs)) -> false()
     , isEmpty(nil()) -> true()
     , isZero(0()) -> true()
     , isZero(s(x)) -> false()
     , head(cons(x, xs)) -> x
     , tail(cons(x, xs)) -> xs
     , tail(nil()) -> nil()
     , p(s(s(x))) -> s(p(s(x)))
     , p(s(0())) -> 0()
     , p(0()) -> 0()
     , inc(s(x)) -> s(inc(x))
     , inc(0()) -> s(0())
     , sumList(xs, y) ->
       if(isEmpty(xs),
          isZero(head(xs)),
          y,
          tail(xs),
          cons(p(head(xs)), tail(xs)),
          inc(y))
     , if(true(), b, y, xs, ys, x) -> y
     , if(false(), true(), y, xs, ys, x) -> sumList(xs, y)
     , if(false(), false(), y, xs, ys, x) -> sumList(ys, x)
     , sum(xs) -> sumList(xs, 0())}

Proof Output:    
  The input cannot be shown compatible