A and B travel back and forth between A and B. At the beginning, they start from A. Land B set off at the same time and walked towards each other. After a period of time, the two met at a distance of 800 meters from the midpoint of the two places. If the center of the ground is 800 meters away, what is the distance between A and B?
甲乙两人在A、B两地往返行驶，开始时两人分别从A．B地同时出发相向而行，经过一段时间后，两人在距离两地中点800米处相遇，两人继续行驶，又过了不少时间两人二次迎面相遇，相遇地点也恰好距离两地中点处800米，那么A、B两地的距离是多少米．
<result>3_200</result>