Comparing installation items saying which level is the last installed

[#1]

Hey guys, so, i have an table like this:

A/C	Instalacao		DESCR_INST	Installed? (Y/N)
4	1		a	Yes
4	1		b	Yes
4	1		c	No
4	1		d	Yes
4	1		e	Yes
4	1		f	Yes
4	1		g	Yes
4	1		h	Yes
4	1		kkkk	Yes
4	2		j	No
4	2		k	No
4	2		l	Yes
4	2		m	Yes
4	2		n	Yes
4	2		o	Yes
4	2		p	Yes
4	2		q	Yes
4	2		r	Yes
4	3		s	Yes
4	3		t	Yes
4	4		u	Yes
4	4		v	Yes
4	5		x	Yes
4	5		y	Yes
4	5		z	No
4	6		w	No
4	6		aa	No
4	6		bb	No
4	6		cc	No
4	6		dd	No
4	6		ee	No
4	6		ff	No

I want to show in a table all the parts that were not installed, but i don't want it to show everything after the last 'Yes'. How do I do that?