Development Assistance Spawn protection help

I need some help with this:

I want to get spawn location, and then Integer from config and tell this to the player if he tries to build in spawn:
You have to go AMOUNT of blocks from spawn to build.
Not just the same amount all the time, but how many blocks remaining until he can build.
Like:
If Integer from config is 10:
You have to go 10 blocks from spawn to build.
You have to go 9 blocks from spawn to build.
You have to go 8 blocks from spawn to build.
You have to go 7 blocks from spawn to build.
etc..
Please help