Teacher Li asks students A, B, and C to talk in the office. A needs 10 minutes to finish talking, B needs 12 minutes to finish talking, and C needs to finish talking in 5 minutes. Minimum total time?
李老师找A、B、C三名同学到办公室谈话，A需10分钟谈完，B需12分钟谈完，C需5分钟谈完，怎样安排三人的谈话顺序，才能使三人等待的总时间最少？
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">12 * 1</gadget>
<output>12</output>

<gadget id="calculator">15 + 20 + 12</gadget>
<output>47</output>

<result>47</result>