$4.$ Write down the characteristics $(1),(2)$ of classes A$,$ B$,$ and C that existed in IPv$4$ classless routing, which is a $($previous$)$ routing method that is not currently in use. Write your answer in the format of $\backslash ($ a b $\backslash )$ and do not calculate it$.$ In the figure below, the $4-$byte IPv$4$ address is displayed on the left in bytes and also written on the right. $(6$ points$)$

class

$(1)$ Maximum number of subnetworks that can be used globally for each class $($hint$)$ When calculating, you should consider that the first few bits are fixed.

$(2)$ Maximum number of hosts that a subnetwork can accommodate