Count unique with two variables

Hi all:

I am trying to find a formula that will count the number of unique occurences with two variables (Department and Period).

Since a person can be listed in the department more than once for each period, I need to find the unique number for each department by period. I have attached a simple file as an example. Any formula would go in the yellow area.

Thanks to all

Max

Perhaps:

L7:
=SUM(IF(FREQUENCY(IF(($E$7:$E$19=$J7)*($F$7:$F$19=$K7),MATCH($G$7:$G$19,$G$7:$G$19,0)),ROW($F$7:$F$19)-ROW($F$7)+1)>0,1))
committed with CTRL + SHIFT + ENTER

copy down as required - remember to reset the array if you alter the formula in anyway.

It works. Thanks a bunch...............

Max