Unique values in a column with duplicates

[rbellotti]

If sheet2 cols A and C equal the value in sheet1 cols H and I, I want to return the number of unique values in sheet 1 column A. Can anyone provide a fiormula for accomplishing this:

The following example should yield a result of 2 for the Arenas/Bibby combination because there are two rows in sheet1 where Arenas is in colH and Bibby in colI, AND the date in colA is unique (10/29/08 and 10/30/08):

sheet2
colA colC
Arenas Bibby

sheet1
colA         colH         colI
10/29/08   Butler       Simmons
10/29/08   Arenas      Bibby
10/29/08   Thomas     Brown
10/30/08   Arenas      Bibby
10/30/08   Stevens    Hale
10/30/08   Arenas      Bibby
10/30/08   Stevens    Simmons
10/31/08   Arenas      Simmons

Thanks,
Bob