TRS:
 {                        r(xs, ys, zs, nil()) -> xs,
                 r(xs, nil(), zs, cons(w, ws)) -> r(xs, xs, cons(succ(zero()), zs), ws),
        r(xs, cons(y, ys), nil(), cons(w, ws)) -> r(xs, xs, cons(succ(zero()), nil()), ws),
  r(xs, cons(y, ys), cons(z, zs), cons(w, ws)) -> r(ys, cons(y, ys), zs, cons(succ(zero()), cons(w, ws)))}
 Fail