In message , Vortex
writes

Any suggestions?

1) Catch cats.

2) Put cats in identical boxes.

3) Take boxes, containing cats, to your local, friendly sub post office.

4) Smile sweetly at sub postmaster, and ask him to weigh the two boxes
on his highly accurate, and regularly checked parcels scales.

5) Return home.

6) Release cats

7) Return to PO, with bottle of wine for sub pm, and weigh empty boxes.

8) Deduct 7 from 4.
--
Graeme