The three students ask the teacher to explain the wrong questions. Xiaoqiang needs 2 minutes, Xiaoming needs 6 minutes, and Xiaohong needs 4 minutes. After the teacher arranges, what is the minimum total waiting and explaining time for the three students?
三名同学找老师讲解错题，小强需要2分钟，小明需要6分钟，小红需要4分钟，经老师安排后，三人最少的等候和讲解时间总和为多少分钟．
<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">6 * 1</gadget>
<output>6</output>

<gadget id="calculator">6 + 8 + 6</gadget>
<output>20</output>

<result>20</result>