Sisi's family had to cross a bridge. It was dark when they crossed the bridge, so there must be lights. Known: It takes 1 minute for Sisi to cross the bridge, 3 minutes for Sisi's elder brother, 6 minutes for Sisi's father, and 8 minutes for Sisi's mother. And this bridge can cross at most two people at a time, and the speed of crossing the bridge depends on the person who crosses the bridge the slowest. There is also a bad condition: the lamp will go out 30 minutes after being lit. May I ask: What is the shortest time for Sisi's family to cross the bridge?
思思一家要过一座桥，过桥的时候是黑夜，所以必须有灯．已知：思思过桥要1分钟，思思的哥哥要3分钟，思思的爸爸要6分钟，思思的妈妈要8分钟．而且这座桥每次最多可过两人，过桥的速度则依过桥最慢者而定．还有一个糟糕的条件：这盏灯在点燃后30分钟就会熄灭．请问：思思一家过桥的最短时间是多少分钟．
<gadget id="calculator">3 + 1 + 8 + 3 + 3</gadget>
<output>18</output>

<result>18</result>