Find Unique Values with a Condition

[gaukin]

Hello,

I currently use an array function to get the number of unique values, however I need to only count those unique values based on a condition. This is the formula I am using to get the number of unique values in column L:

{=SUM(IF(FREQUENCY(MATCH($L$6:$L$20543,$L$6:$L$20543,0),MATCH($L$6:$L$20543,$L$6:$L$20543,0))>0,1))}

but I need to only count those unique values in column L that match a letter (A through E) in column A. I can't figure out where to embed the IF function, or how to change this whole array to a SUMIF.

Thank you!

 

[AhoyNC]

Maybe something like one of these array formulas.
Formula in M2 is unique count for "A" in column A.
Formula in M5 is unique count for any value in column A that is (A thru E).

These are array formulas that must be entered with CTRL-SHIFT-ENTER.

Excel Workbook
	A	B	K	L	M	N
1	Letter				Count
2	A			test1	3	Unique with "A" in column A
3	D			test1
4	A			test1
5	G			test3	6	Unique with "A thru E" in column A
6	D			test3
7	A			test2
8	C			test4
9	G			test5
10	A			test1
11	A			test1
12	A			test5
Sheet