After the fourth brother on the fifth floor got 2345, how to do a good job on the first floor?

Depending on how your house is built, there are 4 rooms on each floor, which can be allocated voluntarily or by lot, as long as there are many ways to divide the house.

The fifth floor is a multi-storey building, 1 to 3 floors are low-rise buildings, 4-6 floors are multi-storey buildings, 7-9 floors are medium-high floors, and 10 or above is high-rise. If it is an elevator, the fifth floor is obviously low.