The older sister and the younger sister run in the same direction along the circular runway. The older sister runs 212 meters per minute, and the younger sister runs 187 meters per minute. They start from the same place. After 16 minutes, the older sister catches up with the younger sister for the first time. Find the length of the runway.
姐姐和妹妹沿环形跑道同方向跑步，姐姐每分钟跑212米，妹妹每分钟跑187米，他们从同一地点出发，16分钟后，姐姐第一次追上妹妹，求跑道的长度．
<gadget id="calculator">212 - 187</gadget>
<output>25</output>

<gadget id="calculator">16 * 25</gadget>
<output>400</output>

<result>400</result>