Suppose that the stop-and-wait protocol is used on a link with a bit rate of 1 kilobyte per second and 0.08 seconds propagation delay. Processing time at nodes is 0.04 sec and no. of bytes in the information frame is 5000. Assume that there are no overhead bytes in the information frame then a number of bytes in acknowledgment frame to achieve a link utilization of at least 80% is _______.