During the school cleaning, students A, B, C, and D each took buckets of different sizes to fetch water together. To fill these buckets, A takes 3 minutes, B takes 5 minutes, C takes 2 minutes, and D takes 4 minutes. Now there is only one faucet, how should the four students be arranged in the order of fetching water so that the total time spent by them is the least? How many minutes is the minimum?
学校大扫除，甲、乙、丙、丁四位同学各拿大小不一的桶一同去打水．注满这些水桶，甲需3分钟，乙需5分钟，丙需2分钟，丁需4分钟．现在只有一个水龙头，应如何安排这四位同学的打水次序，使他们所花费时间总和最少？最少是多少分钟？
<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">2 + 3 + 4</gadget>
<output>9</output>

<gadget id="calculator">2 + 3 + 4 + 5</gadget>
<output>14</output>

<gadget id="calculator">2 + 5 + 9 + 14</gadget>
<output>30</output>

<result>30</result>