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. HostBs window size is 20000 bytes. HostB has already received and acknowledged everything sent by HostAs application up to and including byte #3,454. HostA now sends segments of the same application data stream in order:

P: 173 bytes Q: 347 bytes R: 225 bytes

Suppose that segments P, Q, and R are received, but the acknowledgements for segments P and Q are lost. If there are more segments waiting to be transmitted, what is the sequence number of the next segment transmitted after the ACK for segment R is received?