They accumulate into the top of it.
1	They	they	PRON	PE	Number=Plur|Person=3|PronType=Prs	2	nsubj	_	_
2	accumulate	accumulate	VERB	V	Mood=Ind|Number=Plur|Tense=Pres|VerbForm=Fin	0	root	_	_
3	into	into	ADP	E	_	5	case	_	_
4	the	the	DET	RD	Definite=Def|PronType=Art	5	det	_	_
5	top	top	NOUN	S	Number=Sing	2	obl	_	_
6	of	of	ADP	E	_	7	case	_	_
7	it	it	PRON	PE	Number=Sing|Person=3|PronType=Prs	5	nmod	_	SpaceAfter=No
8	.	.	PUNCT	FS	_	2	punct	_	_
