formula to indicate match exists

Hi all,

I'm relatively new to creating formulas in Excel and having a few problems!

Basically, all I want is for a formula to tell me if I have matching data in two separate cells. What I have is data entered in cell A1. What I would like is one single formula to check if the same entry has been entered in cells A2:A10 and if so, return a 1, and if not return 0.

Hope this makes sense. Thanks for any help in advance.

Luke