Create separate rule

Hello,

I need to set up a buy one get one half off discount.
Let’s say a customer buy 2, the discount would apply.
If the customer buy 3, the discount still apply for the first 2 items then the third item would be at regular price.
If the customer buy 4 then the discount would apply for all 4 items.

Is this possible ? I’m using the free version but do the pro version has this feature ?