The kitten is grilling fish on the stove. Both sides of the fish need to be grilled. It takes 6 minutes to grill each side. Only 2 fish can be grilled at the same time at a time. How long does it take at least to grill 3 fish?
小猫在火炉上烤鱼，鱼的两面都要烤，每烤一面需要6分钟，每次同时只能烤2条鱼，要烤3条鱼，至少需要多少分钟．
<gadget id="calculator">6 + 6 + 6</gadget>
<output>18</output>

<result>18</result>