There are four rooms, each room has no less than 2 people, and the total number of people in any three rooms is no less than 8. What is the minimum number of people in these four rooms?
四个房间，每个房间里不少于2人，任何三个房间里的总人数不少于8人，这四个房间总人数至少有多少人．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">9 + 2</gadget>
<output>11</output>

<result>11</result>