A simple single step Multi.
At the start there are a number of buildings. Let us call the
number A.
On these buildings are some 3 digit numbers.
We want the Largest and Smallest of these.
Call the smallest BCD
and the largest EFG
To calculate the location of the cache you will find it at N59
10.B-E C+G F+D E017 53.C G-A A