Eliminating duplicate numbers via Mac Excel

I imagine you guys have answer this question a zillion times - SORRY I can't seem to find any reference on this.

Original list:

A1: 8
A2: 7
A3: 1
A4: 0
A5: 6
A6: 6

What I'm wanting is to eliminate is any duplicate numbers (6 on this example):

C1: 8
C2: 7
C3: 1
C4: 0
C5: 6
C6: -