What is the factored form of r^27-s^3
r²⁷ - s³r²⁷ + r¹⁸s - r¹⁸s + r⁹s² - r⁹s² - s³r²⁷ + r¹⁸s + r⁹s² - r¹⁸s - r⁹s² - s³r⁹(r¹⁸) + r⁹(r⁹s) + r⁹(s²) - s(r¹⁸) - s(r⁹s) - s(s²)r⁹(r¹⁸ + r⁹s + s²) - s(r¹⁸ + r⁹s + s²)(r⁹ - s)(r¹⁸ + r⁹s + s²)