Get distinct values from multiple non contiguous columns and place them in columns

I have a worksheet with about 25 columns. Every other column up to column N has a list of values 9 rows deep.

I want to get the distinct values from those first non contiguous columns and put them into the last three columns.

Formula:

=IFERROR(IFERROR(INDEX($B$3:$B$11,MATCH(0,COUNTIF($R$2:R2,$B$3:B11&""),0)),IFERROR(INDEX($E$3:$E$11,MATCH(0,COUNTIF($R$2:R2,$E$3:$E$11&""),0)),IFERROR(INDEX($H$3:$H$11,MATCH(0,COUNTIF($R$2:R2,$H$3:H11&""),0)),IFERROR(INDEX($K$3:$K$11,MATCH(0,COUNTIF($R$2:R2,$K$3:$K$11&""),0)),INDEX($N$3:$N$11,MATCH(0,COUNTIF($R$2:R2,$N$3:$N$11&""),0)))))),"")

I have this so far. Problem lies when switching to the next column of those last three.

Any help?