Formula for string length

I am currently working on a game would like to know if anyone by chance knows a formula that finds the length of string or any object when it wraps around a circle…

you have Lf = L1+L2+L3
you have the diameter of the circle(D1)
You also have L1

But what I need is L2 and L3(if I had one I probably could find one)

thanks in advance