The floor a pool holding these addresses has — the highest 1-based index among them, 0
when nothing is attached. An address whose tail is not an index contributes NOTHING rather
than reading as zero: a malformed address must not silently lower a floor.
Parameters
using: readonlystring[]
the addresses attached in that pool
Returns number
the lowest count that keeps every one of them addressable
The floor a pool holding these addresses has — the highest 1-based index among them,
0when nothing is attached. An address whose tail is not an index contributes NOTHING rather than reading as zero: a malformed address must not silently lower a floor.