0 QTRS
digits → d(0) d(x) → if(le(x, s(s(s(s(s(s(s(s(s(0)))))))))), x) if(true, x) → cons(x, d(s(x))) if(false, x) → nil le(0, y) → true le(s(x), 0) → false le(s(x), s(y)) → le(x, y)