Huahua and Yingying set off from places A and B at the same time, respectively, and head towards each other. When Huahua passed 100 meters from the midpoint C of A and B, the two met for the first time; then the two continued to move forward. When Huahua arrived at B, he returned immediately, and after passing 300 meters from C, they met again. After catching up with Yingying, how many meters is the distance between AB and AB?
华华和英英分别从A、B两地同时出发相向而行．当华华经过A、B两地的中点C地100米后，两人第一次相遇；然后两人又继续前进，当华华到达B地后立即返回，又经过C地300米后他追上了英英，则AB两地相距多少米．
<gadget id="calculator">400 / 2</gadget>
<output>200</output>

<gadget id="calculator">200 + 100</gadget>
<output>300</output>

<gadget id="calculator">300 * 2</gadget>
<output>600</output>

<result>600</result>