How to specify inputs using scanf in a particular format
 

Hi,

I want to make a program that accepts the radius of a circle and co-ordinates of the center.
I want the user to specify the inputs as:
radius:{(x,y)}

eg, if the radius is 4, and center is at 1,2, then user should specify it as:
4:{(1,2)}

How to do this in C?