give me an idea for it

it is quite easy to solve infine series of resistance for it you  have only to find out a single unit in structure which repeats in all structure. For example see given structure you can easily say that the structure between c and d repeats in whole digrame and as it is infinite series so assume that the equivalent resistance of this circuit will be r   now replace all circuit after the point E with a single resistance r now it is very easy solve and get the value of r