The distance between two stations in a 10 Mbps LAN using CSM/CD multiple access method is 2,000 meters. Station A sends a long frame first and three micro seconds later, C starts sending a long frame. Notice that when C begins sending, the signal due to the frame from A has not reached station C yet. If it reached, station C would not send it. How many bits from station A have already been sent when it hears the signal from C? Assume propagation speed of the signal in the medium is 200 million meters per second.