and B set off from A and B at the same time, run back and forth between A and B, and meet each other for the first time at 400 meters away from A, and continue to move forward after they meet. The speed is reduced to half of the original speed, and the speed of B is also reduced to half after arriving at point A. As a result, they meet for the second time at a distance of 100 meters from point A. How many meters are the distance between A and B?
甲、乙两人分别从A、B两地同时出发，在A、B两地间往返奔跑，出发后在离A地400米处第一次迎面相遇，相遇之后继续前进，甲到B地后速度变为原来的一半，乙到A地后速度也变为原来的一半，结果他们在距离A地100米处第二次迎面相遇，A、B两地相距多少米？
<gadget id="calculator">400 * 4</gadget>
<output>1_600</output>

<gadget id="calculator">100 * 2 * 4</gadget>
<output>800</output>

<gadget id="calculator">1_600 + 800</gadget>
<output>2_400</output>

<gadget id="calculator">2_400 / 4</gadget>
<output>600</output>

<result>600</result>