Please fix the title change. 'Trivial' and 'elementary' have specific meaning in mathematics and are not interchangeable. Roughly speaking, 'trivial' means easy

Please fix the title change. 'Trivial' and 'elementary' have specific meaning in mathematics and are not interchangeable. Roughly speaking, 'trivial' means easy or obvious, while 'elementary' means a proof that does not use complex analysis or higher techniques. This proof is elementary but definitely not trivial.