Consider a telnet session with a user on host A and a telnet server on host B. The last segment exchanged was from A to B with sequence number=50 and ACK number=90. Assume that there are no packet losses and neither side has any unacknowledged data.

Now, suppose the user types a letter, which results in three segments exchanged between A and B. The second segment is from host ________ to host ________ with sequence number _______ and ACK number _______.