s.hoskin@xtra.co.nz said:

Thanks for piecing together the logic which can at times be difficult to decipher.

Kind wishes,

 Su. 

               _   __  __   ____    _      __     __ __     __
| | | \/ | | _ \ | | \ \ / / \ \ / /
_ _ | | | \ / | | |_) | | |__ \ \_/ / \ \_/ /
| | | | _ | | | |\/| | | _ < | '_ \ \ / \ /
| |_| | | |__| | | | | | | |_) | | |_) | | | | |
\__,_| \____/ |_| |_| |____/ |_.__/ |_| |_|