If there is no ventilation, you can replace the entrance door with a security door with a screen window, and then open a window in the stairwell of the corridor to ventilate the north and south.
Compared with the side door, the middle door has more heating in winter and is sandwiched between the side covers. Generally, only one side will be washed away by rain, so it is not easy to seep. The apartment is more square and the space utilization rate is higher. Generally, the apartment is small, the total price is low and opaque, and the lighting is poor. But not absolutely, it depends on the plan; The apartment is not transparent, and there may be a darkroom. In particular, some recessed intermediate units, although facing south, may not be as good as edge sets.