HostA has established a TCP connection with HostB in a remote network. HostA

is sending packets to HostB. Assume we have configured TCP$,$ somehow, to ACK

every segment $($no ACKing every other segment$).$ Assume that the timeout is the

same for all packets. HostB's "window size" is $20000$ bytes. HostB has already

received and acknowledged everything sent by HostA's application up to

and including byte #$4,978.$ HostA now sends segments of the same application data

stream in order:

P: $168$ bytes

Q: $235$ bytes

R: $437$ bytes

Suppose that packet $P$ is lost, but packets $Q$ and $R$ are received. What is

the acknowledgement number in the ACK for packet R$.$