MAYBE

Problem:
 active(first(0(),X)) -> mark(nil())
 active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z)))
 active(from(X)) -> mark(cons(X,from(s(X))))
 mark(first(X1,X2)) -> active(first(mark(X1),mark(X2)))
 mark(0()) -> active(0())
 mark(nil()) -> active(nil())
 mark(s(X)) -> active(s(mark(X)))
 mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
 mark(from(X)) -> active(from(mark(X)))
 first(mark(X1),X2) -> first(X1,X2)
 first(X1,mark(X2)) -> first(X1,X2)
 first(active(X1),X2) -> first(X1,X2)
 first(X1,active(X2)) -> first(X1,X2)
 s(mark(X)) -> s(X)
 s(active(X)) -> s(X)
 cons(mark(X1),X2) -> cons(X1,X2)
 cons(X1,mark(X2)) -> cons(X1,X2)
 cons(active(X1),X2) -> cons(X1,X2)
 cons(X1,active(X2)) -> cons(X1,X2)
 from(mark(X)) -> from(X)
 from(active(X)) -> from(X)

Proof:
 DP Processor:
  DPs:
   active#(first(0(),X)) -> mark#(nil())
   active#(first(s(X),cons(Y,Z))) -> first#(X,Z)
   active#(first(s(X),cons(Y,Z))) -> cons#(Y,first(X,Z))
   active#(first(s(X),cons(Y,Z))) -> mark#(cons(Y,first(X,Z)))
   active#(from(X)) -> s#(X)
   active#(from(X)) -> from#(s(X))
   active#(from(X)) -> cons#(X,from(s(X)))
   active#(from(X)) -> mark#(cons(X,from(s(X))))
   mark#(first(X1,X2)) -> mark#(X2)
   mark#(first(X1,X2)) -> mark#(X1)
   mark#(first(X1,X2)) -> first#(mark(X1),mark(X2))
   mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2)))
   mark#(0()) -> active#(0())
   mark#(nil()) -> active#(nil())
   mark#(s(X)) -> mark#(X)
   mark#(s(X)) -> s#(mark(X))
   mark#(s(X)) -> active#(s(mark(X)))
   mark#(cons(X1,X2)) -> mark#(X1)
   mark#(cons(X1,X2)) -> cons#(mark(X1),X2)
   mark#(cons(X1,X2)) -> active#(cons(mark(X1),X2))
   mark#(from(X)) -> mark#(X)
   mark#(from(X)) -> from#(mark(X))
   mark#(from(X)) -> active#(from(mark(X)))
   first#(mark(X1),X2) -> first#(X1,X2)
   first#(X1,mark(X2)) -> first#(X1,X2)
   first#(active(X1),X2) -> first#(X1,X2)
   first#(X1,active(X2)) -> first#(X1,X2)
   s#(mark(X)) -> s#(X)
   s#(active(X)) -> s#(X)
   cons#(mark(X1),X2) -> cons#(X1,X2)
   cons#(X1,mark(X2)) -> cons#(X1,X2)
   cons#(active(X1),X2) -> cons#(X1,X2)
   cons#(X1,active(X2)) -> cons#(X1,X2)
   from#(mark(X)) -> from#(X)
   from#(active(X)) -> from#(X)
  TRS:
   active(first(0(),X)) -> mark(nil())
   active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z)))
   active(from(X)) -> mark(cons(X,from(s(X))))
   mark(first(X1,X2)) -> active(first(mark(X1),mark(X2)))
   mark(0()) -> active(0())
   mark(nil()) -> active(nil())
   mark(s(X)) -> active(s(mark(X)))
   mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
   mark(from(X)) -> active(from(mark(X)))
   first(mark(X1),X2) -> first(X1,X2)
   first(X1,mark(X2)) -> first(X1,X2)
   first(active(X1),X2) -> first(X1,X2)
   first(X1,active(X2)) -> first(X1,X2)
   s(mark(X)) -> s(X)
   s(active(X)) -> s(X)
   cons(mark(X1),X2) -> cons(X1,X2)
   cons(X1,mark(X2)) -> cons(X1,X2)
   cons(active(X1),X2) -> cons(X1,X2)
   cons(X1,active(X2)) -> cons(X1,X2)
   from(mark(X)) -> from(X)
   from(active(X)) -> from(X)
  CDG Processor:
   DPs:
    active#(first(0(),X)) -> mark#(nil())
    active#(first(s(X),cons(Y,Z))) -> first#(X,Z)
    active#(first(s(X),cons(Y,Z))) -> cons#(Y,first(X,Z))
    active#(first(s(X),cons(Y,Z))) -> mark#(cons(Y,first(X,Z)))
    active#(from(X)) -> s#(X)
    active#(from(X)) -> from#(s(X))
    active#(from(X)) -> cons#(X,from(s(X)))
    active#(from(X)) -> mark#(cons(X,from(s(X))))
    mark#(first(X1,X2)) -> mark#(X2)
    mark#(first(X1,X2)) -> mark#(X1)
    mark#(first(X1,X2)) -> first#(mark(X1),mark(X2))
    mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2)))
    mark#(0()) -> active#(0())
    mark#(nil()) -> active#(nil())
    mark#(s(X)) -> mark#(X)
    mark#(s(X)) -> s#(mark(X))
    mark#(s(X)) -> active#(s(mark(X)))
    mark#(cons(X1,X2)) -> mark#(X1)
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2)
    mark#(cons(X1,X2)) -> active#(cons(mark(X1),X2))
    mark#(from(X)) -> mark#(X)
    mark#(from(X)) -> from#(mark(X))
    mark#(from(X)) -> active#(from(mark(X)))
    first#(mark(X1),X2) -> first#(X1,X2)
    first#(X1,mark(X2)) -> first#(X1,X2)
    first#(active(X1),X2) -> first#(X1,X2)
    first#(X1,active(X2)) -> first#(X1,X2)
    s#(mark(X)) -> s#(X)
    s#(active(X)) -> s#(X)
    cons#(mark(X1),X2) -> cons#(X1,X2)
    cons#(X1,mark(X2)) -> cons#(X1,X2)
    cons#(active(X1),X2) -> cons#(X1,X2)
    cons#(X1,active(X2)) -> cons#(X1,X2)
    from#(mark(X)) -> from#(X)
    from#(active(X)) -> from#(X)
   TRS:
    active(first(0(),X)) -> mark(nil())
    active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z)))
    active(from(X)) -> mark(cons(X,from(s(X))))
    mark(first(X1,X2)) -> active(first(mark(X1),mark(X2)))
    mark(0()) -> active(0())
    mark(nil()) -> active(nil())
    mark(s(X)) -> active(s(mark(X)))
    mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
    mark(from(X)) -> active(from(mark(X)))
    first(mark(X1),X2) -> first(X1,X2)
    first(X1,mark(X2)) -> first(X1,X2)
    first(active(X1),X2) -> first(X1,X2)
    first(X1,active(X2)) -> first(X1,X2)
    s(mark(X)) -> s(X)
    s(active(X)) -> s(X)
    cons(mark(X1),X2) -> cons(X1,X2)
    cons(X1,mark(X2)) -> cons(X1,X2)
    cons(active(X1),X2) -> cons(X1,X2)
    cons(X1,active(X2)) -> cons(X1,X2)
    from(mark(X)) -> from(X)
    from(active(X)) -> from(X)
   graph:
    from#(mark(X)) -> from#(X) -> from#(mark(X)) -> from#(X)
    from#(mark(X)) -> from#(X) -> from#(active(X)) -> from#(X)
    from#(active(X)) -> from#(X) -> from#(mark(X)) -> from#(X)
    from#(active(X)) -> from#(X) -> from#(active(X)) -> from#(X)
    s#(mark(X)) -> s#(X) -> s#(mark(X)) -> s#(X)
    s#(mark(X)) -> s#(X) -> s#(active(X)) -> s#(X)
    s#(active(X)) -> s#(X) -> s#(mark(X)) -> s#(X)
    s#(active(X)) -> s#(X) -> s#(active(X)) -> s#(X)
    cons#(mark(X1),X2) -> cons#(X1,X2) ->
    cons#(mark(X1),X2) -> cons#(X1,X2)
    cons#(mark(X1),X2) -> cons#(X1,X2) ->
    cons#(X1,mark(X2)) -> cons#(X1,X2)
    cons#(mark(X1),X2) -> cons#(X1,X2) ->
    cons#(active(X1),X2) -> cons#(X1,X2)
    cons#(mark(X1),X2) -> cons#(X1,X2) ->
    cons#(X1,active(X2)) -> cons#(X1,X2)
    cons#(active(X1),X2) -> cons#(X1,X2) ->
    cons#(mark(X1),X2) -> cons#(X1,X2)
    cons#(active(X1),X2) -> cons#(X1,X2) ->
    cons#(X1,mark(X2)) -> cons#(X1,X2)
    cons#(active(X1),X2) -> cons#(X1,X2) ->
    cons#(active(X1),X2) -> cons#(X1,X2)
    cons#(active(X1),X2) -> cons#(X1,X2) ->
    cons#(X1,active(X2)) -> cons#(X1,X2)
    cons#(X1,mark(X2)) -> cons#(X1,X2) ->
    cons#(mark(X1),X2) -> cons#(X1,X2)
    cons#(X1,mark(X2)) -> cons#(X1,X2) ->
    cons#(X1,mark(X2)) -> cons#(X1,X2)
    cons#(X1,mark(X2)) -> cons#(X1,X2) ->
    cons#(active(X1),X2) -> cons#(X1,X2)
    cons#(X1,mark(X2)) -> cons#(X1,X2) ->
    cons#(X1,active(X2)) -> cons#(X1,X2)
    cons#(X1,active(X2)) -> cons#(X1,X2) ->
    cons#(mark(X1),X2) -> cons#(X1,X2)
    cons#(X1,active(X2)) -> cons#(X1,X2) ->
    cons#(X1,mark(X2)) -> cons#(X1,X2)
    cons#(X1,active(X2)) -> cons#(X1,X2) ->
    cons#(active(X1),X2) -> cons#(X1,X2)
    cons#(X1,active(X2)) -> cons#(X1,X2) ->
    cons#(X1,active(X2)) -> cons#(X1,X2)
    first#(mark(X1),X2) -> first#(X1,X2) ->
    first#(mark(X1),X2) -> first#(X1,X2)
    first#(mark(X1),X2) -> first#(X1,X2) ->
    first#(X1,mark(X2)) -> first#(X1,X2)
    first#(mark(X1),X2) -> first#(X1,X2) ->
    first#(active(X1),X2) -> first#(X1,X2)
    first#(mark(X1),X2) -> first#(X1,X2) ->
    first#(X1,active(X2)) -> first#(X1,X2)
    first#(active(X1),X2) -> first#(X1,X2) ->
    first#(mark(X1),X2) -> first#(X1,X2)
    first#(active(X1),X2) -> first#(X1,X2) ->
    first#(X1,mark(X2)) -> first#(X1,X2)
    first#(active(X1),X2) -> first#(X1,X2) ->
    first#(active(X1),X2) -> first#(X1,X2)
    first#(active(X1),X2) -> first#(X1,X2) ->
    first#(X1,active(X2)) -> first#(X1,X2)
    first#(X1,mark(X2)) -> first#(X1,X2) ->
    first#(mark(X1),X2) -> first#(X1,X2)
    first#(X1,mark(X2)) -> first#(X1,X2) ->
    first#(X1,mark(X2)) -> first#(X1,X2)
    first#(X1,mark(X2)) -> first#(X1,X2) ->
    first#(active(X1),X2) -> first#(X1,X2)
    first#(X1,mark(X2)) -> first#(X1,X2) ->
    first#(X1,active(X2)) -> first#(X1,X2)
    first#(X1,active(X2)) -> first#(X1,X2) ->
    first#(mark(X1),X2) -> first#(X1,X2)
    first#(X1,active(X2)) -> first#(X1,X2) ->
    first#(X1,mark(X2)) -> first#(X1,X2)
    first#(X1,active(X2)) -> first#(X1,X2) ->
    first#(active(X1),X2) -> first#(X1,X2)
    first#(X1,active(X2)) -> first#(X1,X2) ->
    first#(X1,active(X2)) -> first#(X1,X2)
    mark#(from(X)) -> from#(mark(X)) -> from#(mark(X)) -> from#(X)
    mark#(from(X)) -> from#(mark(X)) -> from#(active(X)) -> from#(X)
    mark#(from(X)) -> mark#(X) -> mark#(first(X1,X2)) -> mark#(X2)
    mark#(from(X)) -> mark#(X) -> mark#(first(X1,X2)) -> mark#(X1)
    mark#(from(X)) -> mark#(X) ->
    mark#(first(X1,X2)) -> first#(mark(X1),mark(X2))
    mark#(from(X)) -> mark#(X) ->
    mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2)))
    mark#(from(X)) -> mark#(X) -> mark#(0()) -> active#(0())
    mark#(from(X)) -> mark#(X) -> mark#(nil()) -> active#(nil())
    mark#(from(X)) -> mark#(X) -> mark#(s(X)) -> mark#(X)
    mark#(from(X)) -> mark#(X) -> mark#(s(X)) -> s#(mark(X))
    mark#(from(X)) -> mark#(X) -> mark#(s(X)) -> active#(s(mark(X)))
    mark#(from(X)) -> mark#(X) -> mark#(cons(X1,X2)) -> mark#(X1)
    mark#(from(X)) -> mark#(X) ->
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2)
    mark#(from(X)) -> mark#(X) ->
    mark#(cons(X1,X2)) -> active#(cons(mark(X1),X2))
    mark#(from(X)) -> mark#(X) -> mark#(from(X)) -> mark#(X)
    mark#(from(X)) -> mark#(X) -> mark#(from(X)) -> from#(mark(X))
    mark#(from(X)) -> mark#(X) ->
    mark#(from(X)) -> active#(from(mark(X)))
    mark#(from(X)) -> active#(from(mark(X))) ->
    active#(from(X)) -> s#(X)
    mark#(from(X)) -> active#(from(mark(X))) ->
    active#(from(X)) -> from#(s(X))
    mark#(from(X)) -> active#(from(mark(X))) ->
    active#(from(X)) -> cons#(X,from(s(X)))
    mark#(from(X)) -> active#(from(mark(X))) ->
    active#(from(X)) -> mark#(cons(X,from(s(X))))
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2) ->
    cons#(mark(X1),X2) -> cons#(X1,X2)
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2) ->
    cons#(X1,mark(X2)) -> cons#(X1,X2)
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2) ->
    cons#(active(X1),X2) -> cons#(X1,X2)
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2) ->
    cons#(X1,active(X2)) -> cons#(X1,X2)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(first(X1,X2)) -> mark#(X2)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(first(X1,X2)) -> mark#(X1)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(first(X1,X2)) -> first#(mark(X1),mark(X2))
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2)))
    mark#(cons(X1,X2)) -> mark#(X1) -> mark#(0()) -> active#(0())
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(nil()) -> active#(nil())
    mark#(cons(X1,X2)) -> mark#(X1) -> mark#(s(X)) -> mark#(X)
    mark#(cons(X1,X2)) -> mark#(X1) -> mark#(s(X)) -> s#(mark(X))
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(s(X)) -> active#(s(mark(X)))
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(cons(X1,X2)) -> mark#(X1)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(cons(X1,X2)) -> active#(cons(mark(X1),X2))
    mark#(cons(X1,X2)) -> mark#(X1) -> mark#(from(X)) -> mark#(X)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(from(X)) -> from#(mark(X))
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(from(X)) -> active#(from(mark(X)))
    mark#(s(X)) -> s#(mark(X)) -> s#(mark(X)) -> s#(X)
    mark#(s(X)) -> s#(mark(X)) -> s#(active(X)) -> s#(X)
    mark#(s(X)) -> mark#(X) -> mark#(first(X1,X2)) -> mark#(X2)
    mark#(s(X)) -> mark#(X) -> mark#(first(X1,X2)) -> mark#(X1)
    mark#(s(X)) -> mark#(X) ->
    mark#(first(X1,X2)) -> first#(mark(X1),mark(X2))
    mark#(s(X)) -> mark#(X) ->
    mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2)))
    mark#(s(X)) -> mark#(X) -> mark#(0()) -> active#(0())
    mark#(s(X)) -> mark#(X) -> mark#(nil()) -> active#(nil())
    mark#(s(X)) -> mark#(X) -> mark#(s(X)) -> mark#(X)
    mark#(s(X)) -> mark#(X) -> mark#(s(X)) -> s#(mark(X))
    mark#(s(X)) -> mark#(X) -> mark#(s(X)) -> active#(s(mark(X)))
    mark#(s(X)) -> mark#(X) -> mark#(cons(X1,X2)) -> mark#(X1)
    mark#(s(X)) -> mark#(X) -> mark#(cons(X1,X2)) -> cons#(mark(X1),X2)
    mark#(s(X)) -> mark#(X) ->
    mark#(cons(X1,X2)) -> active#(cons(mark(X1),X2))
    mark#(s(X)) -> mark#(X) -> mark#(from(X)) -> mark#(X)
    mark#(s(X)) -> mark#(X) -> mark#(from(X)) -> from#(mark(X))
    mark#(s(X)) -> mark#(X) ->
    mark#(from(X)) -> active#(from(mark(X)))
    mark#(first(X1,X2)) -> first#(mark(X1),mark(X2)) ->
    first#(mark(X1),X2) -> first#(X1,X2)
    mark#(first(X1,X2)) -> first#(mark(X1),mark(X2)) ->
    first#(X1,mark(X2)) -> first#(X1,X2)
    mark#(first(X1,X2)) -> first#(mark(X1),mark(X2)) ->
    first#(active(X1),X2) -> first#(X1,X2)
    mark#(first(X1,X2)) -> first#(mark(X1),mark(X2)) ->
    first#(X1,active(X2)) -> first#(X1,X2)
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(first(X1,X2)) -> mark#(X2)
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(first(X1,X2)) -> mark#(X1)
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(first(X1,X2)) -> first#(mark(X1),mark(X2))
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2)))
    mark#(first(X1,X2)) -> mark#(X2) -> mark#(0()) -> active#(0())
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(nil()) -> active#(nil())
    mark#(first(X1,X2)) -> mark#(X2) -> mark#(s(X)) -> mark#(X)
    mark#(first(X1,X2)) -> mark#(X2) -> mark#(s(X)) -> s#(mark(X))
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(s(X)) -> active#(s(mark(X)))
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(cons(X1,X2)) -> mark#(X1)
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2)
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(cons(X1,X2)) -> active#(cons(mark(X1),X2))
    mark#(first(X1,X2)) -> mark#(X2) -> mark#(from(X)) -> mark#(X)
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(from(X)) -> from#(mark(X))
    mark#(first(X1,X2)) -> mark#(X2) ->
    mark#(from(X)) -> active#(from(mark(X)))
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(first(X1,X2)) -> mark#(X2)
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(first(X1,X2)) -> mark#(X1)
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(first(X1,X2)) -> first#(mark(X1),mark(X2))
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2)))
    mark#(first(X1,X2)) -> mark#(X1) -> mark#(0()) -> active#(0())
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(nil()) -> active#(nil())
    mark#(first(X1,X2)) -> mark#(X1) -> mark#(s(X)) -> mark#(X)
    mark#(first(X1,X2)) -> mark#(X1) -> mark#(s(X)) -> s#(mark(X))
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(s(X)) -> active#(s(mark(X)))
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(cons(X1,X2)) -> mark#(X1)
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2)
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(cons(X1,X2)) -> active#(cons(mark(X1),X2))
    mark#(first(X1,X2)) -> mark#(X1) -> mark#(from(X)) -> mark#(X)
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(from(X)) -> from#(mark(X))
    mark#(first(X1,X2)) -> mark#(X1) ->
    mark#(from(X)) -> active#(from(mark(X)))
    mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2))) ->
    active#(first(0(),X)) -> mark#(nil())
    mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2))) ->
    active#(first(s(X),cons(Y,Z))) -> first#(X,Z)
    mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2))) ->
    active#(first(s(X),cons(Y,Z))) -> cons#(Y,first(X,Z))
    mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2))) ->
    active#(first(s(X),cons(Y,Z))) -> mark#(cons(Y,first(X,Z)))
    active#(from(X)) -> s#(X) -> s#(mark(X)) -> s#(X)
    active#(from(X)) -> s#(X) -> s#(active(X)) -> s#(X)
    active#(from(X)) -> cons#(X,from(s(X))) ->
    cons#(mark(X1),X2) -> cons#(X1,X2)
    active#(from(X)) -> cons#(X,from(s(X))) ->
    cons#(active(X1),X2) -> cons#(X1,X2)
    active#(from(X)) -> mark#(cons(X,from(s(X)))) ->
    mark#(cons(X1,X2)) -> mark#(X1)
    active#(from(X)) -> mark#(cons(X,from(s(X)))) ->
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2)
    active#(from(X)) -> mark#(cons(X,from(s(X)))) ->
    mark#(cons(X1,X2)) -> active#(cons(mark(X1),X2))
    active#(first(s(X),cons(Y,Z))) -> cons#(Y,first(X,Z)) ->
    cons#(mark(X1),X2) -> cons#(X1,X2)
    active#(first(s(X),cons(Y,Z))) -> cons#(Y,first(X,Z)) ->
    cons#(active(X1),X2) -> cons#(X1,X2)
    active#(first(s(X),cons(Y,Z))) -> first#(X,Z) ->
    first#(mark(X1),X2) -> first#(X1,X2)
    active#(first(s(X),cons(Y,Z))) -> first#(X,Z) ->
    first#(X1,mark(X2)) -> first#(X1,X2)
    active#(first(s(X),cons(Y,Z))) -> first#(X,Z) ->
    first#(active(X1),X2) -> first#(X1,X2)
    active#(first(s(X),cons(Y,Z))) -> first#(X,Z) ->
    first#(X1,active(X2)) -> first#(X1,X2)
    active#(first(s(X),cons(Y,Z))) -> mark#(cons(Y,first(X,Z))) ->
    mark#(cons(X1,X2)) -> mark#(X1)
    active#(first(s(X),cons(Y,Z))) -> mark#(cons(Y,first(X,Z))) ->
    mark#(cons(X1,X2)) -> cons#(mark(X1),X2)
    active#(first(s(X),cons(Y,Z))) -> mark#(cons(Y,first(X,Z))) ->
    mark#(cons(X1,X2)) -> active#(cons(mark(X1),X2))
    active#(first(0(),X)) -> mark#(nil()) -> mark#(nil()) -> active#(nil())
   Restore Modifier:
    DPs:
     active#(first(0(),X)) -> mark#(nil())
     active#(first(s(X),cons(Y,Z))) -> first#(X,Z)
     active#(first(s(X),cons(Y,Z))) -> cons#(Y,first(X,Z))
     active#(first(s(X),cons(Y,Z))) -> mark#(cons(Y,first(X,Z)))
     active#(from(X)) -> s#(X)
     active#(from(X)) -> from#(s(X))
     active#(from(X)) -> cons#(X,from(s(X)))
     active#(from(X)) -> mark#(cons(X,from(s(X))))
     mark#(first(X1,X2)) -> mark#(X2)
     mark#(first(X1,X2)) -> mark#(X1)
     mark#(first(X1,X2)) -> first#(mark(X1),mark(X2))
     mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2)))
     mark#(0()) -> active#(0())
     mark#(nil()) -> active#(nil())
     mark#(s(X)) -> mark#(X)
     mark#(s(X)) -> s#(mark(X))
     mark#(s(X)) -> active#(s(mark(X)))
     mark#(cons(X1,X2)) -> mark#(X1)
     mark#(cons(X1,X2)) -> cons#(mark(X1),X2)
     mark#(cons(X1,X2)) -> active#(cons(mark(X1),X2))
     mark#(from(X)) -> mark#(X)
     mark#(from(X)) -> from#(mark(X))
     mark#(from(X)) -> active#(from(mark(X)))
     first#(mark(X1),X2) -> first#(X1,X2)
     first#(X1,mark(X2)) -> first#(X1,X2)
     first#(active(X1),X2) -> first#(X1,X2)
     first#(X1,active(X2)) -> first#(X1,X2)
     s#(mark(X)) -> s#(X)
     s#(active(X)) -> s#(X)
     cons#(mark(X1),X2) -> cons#(X1,X2)
     cons#(X1,mark(X2)) -> cons#(X1,X2)
     cons#(active(X1),X2) -> cons#(X1,X2)
     cons#(X1,active(X2)) -> cons#(X1,X2)
     from#(mark(X)) -> from#(X)
     from#(active(X)) -> from#(X)
    TRS:
     active(first(0(),X)) -> mark(nil())
     active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z)))
     active(from(X)) -> mark(cons(X,from(s(X))))
     mark(first(X1,X2)) -> active(first(mark(X1),mark(X2)))
     mark(0()) -> active(0())
     mark(nil()) -> active(nil())
     mark(s(X)) -> active(s(mark(X)))
     mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
     mark(from(X)) -> active(from(mark(X)))
     first(mark(X1),X2) -> first(X1,X2)
     first(X1,mark(X2)) -> first(X1,X2)
     first(active(X1),X2) -> first(X1,X2)
     first(X1,active(X2)) -> first(X1,X2)
     s(mark(X)) -> s(X)
     s(active(X)) -> s(X)
     cons(mark(X1),X2) -> cons(X1,X2)
     cons(X1,mark(X2)) -> cons(X1,X2)
     cons(active(X1),X2) -> cons(X1,X2)
     cons(X1,active(X2)) -> cons(X1,X2)
     from(mark(X)) -> from(X)
     from(active(X)) -> from(X)
    SCC Processor:
     #sccs: 5
     #rules: 21
     #arcs: 152/1225
     DPs:
      mark#(from(X)) -> mark#(X)
      mark#(from(X)) -> active#(from(mark(X)))
      active#(from(X)) -> mark#(cons(X,from(s(X))))
      mark#(cons(X1,X2)) -> mark#(X1)
      mark#(s(X)) -> mark#(X)
      mark#(first(X1,X2)) -> active#(first(mark(X1),mark(X2)))
      active#(first(s(X),cons(Y,Z))) -> mark#(cons(Y,first(X,Z)))
      mark#(first(X1,X2)) -> mark#(X1)
      mark#(first(X1,X2)) -> mark#(X2)
     TRS:
      active(first(0(),X)) -> mark(nil())
      active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z)))
      active(from(X)) -> mark(cons(X,from(s(X))))
      mark(first(X1,X2)) -> active(first(mark(X1),mark(X2)))
      mark(0()) -> active(0())
      mark(nil()) -> active(nil())
      mark(s(X)) -> active(s(mark(X)))
      mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
      mark(from(X)) -> active(from(mark(X)))
      first(mark(X1),X2) -> first(X1,X2)
      first(X1,mark(X2)) -> first(X1,X2)
      first(active(X1),X2) -> first(X1,X2)
      first(X1,active(X2)) -> first(X1,X2)
      s(mark(X)) -> s(X)
      s(active(X)) -> s(X)
      cons(mark(X1),X2) -> cons(X1,X2)
      cons(X1,mark(X2)) -> cons(X1,X2)
      cons(active(X1),X2) -> cons(X1,X2)
      cons(X1,active(X2)) -> cons(X1,X2)
      from(mark(X)) -> from(X)
      from(active(X)) -> from(X)
     Open
     
     DPs:
      first#(mark(X1),X2) -> first#(X1,X2)
      first#(X1,active(X2)) -> first#(X1,X2)
      first#(active(X1),X2) -> first#(X1,X2)
      first#(X1,mark(X2)) -> first#(X1,X2)
     TRS:
      active(first(0(),X)) -> mark(nil())
      active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z)))
      active(from(X)) -> mark(cons(X,from(s(X))))
      mark(first(X1,X2)) -> active(first(mark(X1),mark(X2)))
      mark(0()) -> active(0())
      mark(nil()) -> active(nil())
      mark(s(X)) -> active(s(mark(X)))
      mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
      mark(from(X)) -> active(from(mark(X)))
      first(mark(X1),X2) -> first(X1,X2)
      first(X1,mark(X2)) -> first(X1,X2)
      first(active(X1),X2) -> first(X1,X2)
      first(X1,active(X2)) -> first(X1,X2)
      s(mark(X)) -> s(X)
      s(active(X)) -> s(X)
      cons(mark(X1),X2) -> cons(X1,X2)
      cons(X1,mark(X2)) -> cons(X1,X2)
      cons(active(X1),X2) -> cons(X1,X2)
      cons(X1,active(X2)) -> cons(X1,X2)
      from(mark(X)) -> from(X)
      from(active(X)) -> from(X)
     Open
     
     DPs:
      cons#(mark(X1),X2) -> cons#(X1,X2)
      cons#(X1,active(X2)) -> cons#(X1,X2)
      cons#(active(X1),X2) -> cons#(X1,X2)
      cons#(X1,mark(X2)) -> cons#(X1,X2)
     TRS:
      active(first(0(),X)) -> mark(nil())
      active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z)))
      active(from(X)) -> mark(cons(X,from(s(X))))
      mark(first(X1,X2)) -> active(first(mark(X1),mark(X2)))
      mark(0()) -> active(0())
      mark(nil()) -> active(nil())
      mark(s(X)) -> active(s(mark(X)))
      mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
      mark(from(X)) -> active(from(mark(X)))
      first(mark(X1),X2) -> first(X1,X2)
      first(X1,mark(X2)) -> first(X1,X2)
      first(active(X1),X2) -> first(X1,X2)
      first(X1,active(X2)) -> first(X1,X2)
      s(mark(X)) -> s(X)
      s(active(X)) -> s(X)
      cons(mark(X1),X2) -> cons(X1,X2)
      cons(X1,mark(X2)) -> cons(X1,X2)
      cons(active(X1),X2) -> cons(X1,X2)
      cons(X1,active(X2)) -> cons(X1,X2)
      from(mark(X)) -> from(X)
      from(active(X)) -> from(X)
     Open
     
     DPs:
      s#(mark(X)) -> s#(X)
      s#(active(X)) -> s#(X)
     TRS:
      active(first(0(),X)) -> mark(nil())
      active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z)))
      active(from(X)) -> mark(cons(X,from(s(X))))
      mark(first(X1,X2)) -> active(first(mark(X1),mark(X2)))
      mark(0()) -> active(0())
      mark(nil()) -> active(nil())
      mark(s(X)) -> active(s(mark(X)))
      mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
      mark(from(X)) -> active(from(mark(X)))
      first(mark(X1),X2) -> first(X1,X2)
      first(X1,mark(X2)) -> first(X1,X2)
      first(active(X1),X2) -> first(X1,X2)
      first(X1,active(X2)) -> first(X1,X2)
      s(mark(X)) -> s(X)
      s(active(X)) -> s(X)
      cons(mark(X1),X2) -> cons(X1,X2)
      cons(X1,mark(X2)) -> cons(X1,X2)
      cons(active(X1),X2) -> cons(X1,X2)
      cons(X1,active(X2)) -> cons(X1,X2)
      from(mark(X)) -> from(X)
      from(active(X)) -> from(X)
     Open
     
     DPs:
      from#(mark(X)) -> from#(X)
      from#(active(X)) -> from#(X)
     TRS:
      active(first(0(),X)) -> mark(nil())
      active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z)))
      active(from(X)) -> mark(cons(X,from(s(X))))
      mark(first(X1,X2)) -> active(first(mark(X1),mark(X2)))
      mark(0()) -> active(0())
      mark(nil()) -> active(nil())
      mark(s(X)) -> active(s(mark(X)))
      mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
      mark(from(X)) -> active(from(mark(X)))
      first(mark(X1),X2) -> first(X1,X2)
      first(X1,mark(X2)) -> first(X1,X2)
      first(active(X1),X2) -> first(X1,X2)
      first(X1,active(X2)) -> first(X1,X2)
      s(mark(X)) -> s(X)
      s(active(X)) -> s(X)
      cons(mark(X1),X2) -> cons(X1,X2)
      cons(X1,mark(X2)) -> cons(X1,X2)
      cons(active(X1),X2) -> cons(X1,X2)
      cons(X1,active(X2)) -> cons(X1,X2)
      from(mark(X)) -> from(X)
      from(active(X)) -> from(X)
     Open