Using Go$-$back$-$N protocol, assume that the timeout values for the protocol is sufficiently long such that $5$ consecutive data segments and the corresponding ACKs can be received $($if not lost in the channel$)$ by the receiving host $($B$)$ and the sending host $($A$),$ respectively. Suppose host A sends $5$ data segments to host B$,$ and the second segment $($sent from A$)$ is lost. In the end, all $5$ data segments have been correctly received by host B$.$ How many segments have host A sent in total, and how many ACKs has host B sent in total? What is their sequence number?