Excel - Multiple Variables, Multiple Returns

Hi,

I've been driving myself crazy on excel trying to figure out a formula to calculate the responses for a test. Here's what I need it to do:

If the value in cell A2 matches the value in cell B2, I need it to display a 1.
If the value in cell A2 does NOT match the value in cell B2 and is not blank, I need it to subtract .25 or display -.25 (whichever).
If there is no value in cell A2 (if it's blank), I need it to display 0.

I can't find this anywhere because nothing explains how to pick between 3 inputs and then return one of 3 values.

Hope you can help.>