Hi John o'A.
I think that's a really clever thing that you did there. Did the wine help before or after you had solved it (or both)?
Arran must be a peaceful place if you are able to get that worked out without interruption!
Sorry about the negative integers - I thought that, maybe, this was one of those puzzles that didn't need the brute force of working out each and every solution, but just some 'trick' or other.
JimC