It should be 4 - easy.
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	4	nsubj	4:nsubj	_
2	should	should	AUX	MD	VerbForm=Fin	4	aux	4:aux	_
3	be	be	AUX	VB	VerbForm=Inf	4	cop	4:cop	_
4	4	4	NUM	CD	NumForm=Digit|NumType=Card	0	root	0:root	_
5	-	-	PUNCT	,	_	4	punct	4:punct	_
6	easy	easy	ADJ	JJ	Degree=Pos	4	amod	4:amod	SpaceAfter=No
7	.	.	PUNCT	.	_	4	punct	4:punct	_
