no idea of it is serious 
(ROOT (S (NP (NP (DT no) (NN idea)) (PP (IN of) (NP (PRP it)))) (VP (VBZ is) (ADJP (JJ serious)))))
(ROOT (S (NP (NP (DT ) (NN )) (PP (IN ) (NP (PRP )))) (VP (VBZ ) (ADJP (JJ )))))