Excel 2003 on Windows XP.

Sheet1
A1:A10, named Category, contains "A", "B" or "C".
B1:B10, named Code, contains a code number as text. Items are not unique.

Sample data:

A 1-1
A 1-1
A 1-2
A 1-2
B 1-1
B 1-2
B 1-3
C 1-1
C 1-1
C 1-1
C 1-1

Sheet2
Column A contains the possible categories.
In column B, I need a formula that will give me a count of unique codes for
a given category.

Sample desired result:

A 2
B 3
C 1

Unique I can do. Unique with conditions, I can't figure out. Any help is
greatly appreciated.

Thanks,
Tim C