TRS:
 {    -(x, 0()) -> x,
  -(s(x), s(y)) -> -(x, y),
        p(s(x)) -> x,
     f(s(x), y) -> f(p(-(s(x), y)), p(-(y, s(x)))),
     f(x, s(y)) -> f(p(-(x, s(y))), p(-(s(y), x)))}
 Fail