Count Unique Items

In column A, I have numbers, for example:

12345
6789
654368
88535
7878545
12345
6789
88535
45757

Some of these numbers, as you can see, repeat. I want to count how many unique numbers there are in column A. If I used the above example, the number would be 6. Thank you very much for your help.

=SUMPRODUCT( 1 / COUNTIF(A1:A9, A1:A9) )

Worked GREAT!
Thank you very much for your help!