circuit analysis - Finding equivalent resistance?

The image shown right below is a schematic diagram of the circuit.

There we need to find the equivalent resistance through X and Y.

I reduce the inner most resistors , because I figure out that there is a Wheatstone bridge out there, the resistance that I removed are shown below.

How can I proceed further , I have no idea , I am stuck on this .How could I proceed further and find the equivalent resistance through X and Y ?