Pier A is upstream of Pier B, and the "No. 2005" remote control ship model departs from Pier A and sails back and forth between the two piers. It is known that the speed of the ship model in still water is 200 meters per minute, and the speed of the current is 40 meters per minute. 20 minutes after departure, the ship model is located 960 meters downstream of Pier A and heading towards Pier B. Find the distance between port A and port B.
A码头在B码头的上游，"2005号"遥控舰模从A码头出发，在两个码头之间往返航行．已知舰模在静水中的速度是每分钟200米，水流的速度是每分钟40米．出发20分钟后，舰模位于A码头下游960米处，并向B码头行驶．求A码头和B码头之间的距离．
<result>1_536</result>