There are four rooms, and there are no less than 4 people in each room. If the total number of people in any three rooms is not less than 14, then the total number of people in these four rooms is at least how many people.
有四个房间，每个房间里不少于4人，如果任意三个房间里的总人数不少于14人，那么这四个房间里的总人数至少有多少人．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">15 + 4</gadget>
<output>19</output>

<result>19</result>