David W. answered 11/30/18
Experienced Prof
Diagrams, even though they are rough sketches and not to scale, are very helpful !!,
Floor
12 START
11 Down 1
10 Down 2
9 Down 3
8 Down 4
7 Down 5
6 Down 6
5 Down 7
5 Down 8
3 Down 9
2 Down 19
1 Down 11
Note that the first floor is ground level' there is no Floor 0.
Now, take it back up five floors (is this easy, or what?)