Sample - Data Set.zip

I want to count the unique cells in Column A That have a number in Column C

A B C D
C20358 Carriage House; The 479220 $84.11
C20449 Historic Tamarack Lodge 481341 $29.97
C20449 Historic Tamarack Lodge 520668 $9.54
C20457 Old Forge Camping Resort 480541 $176.04


The answer should be 3

C20358
C20449
C20457