Calculation of number of molecules at special distance

Hello everyone,
I want to find the number of solvent molecules at a special distance from solute molecule. My simulated system is a polymer solution, in which a polymer chain (as solute) was placed in simulation box and then solvent molecules were packed in the box. Now I try to fine, after main simulation, how many solvent molecules are located at a special distance from the polymer chain.
Would you tell me your ideas that how I can do that?

Best Regards
Sousa