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 \#4,422. HostA now sends segments of the same application data stream in order: P: 391 bytes Q: 221 bytes R: 326 bytes Suppose the segments arrive at Host B in the order Q,P, and R. What is the acknowledgment number on the segment sent in response to segment