In a calligraphy competition, a total of 20 people in the fourth and fifth grades won prizes. Among the winners, 16 were not in the fourth grade, and 12 were not in the fifth grade. What is the total number of winners in this calligraphy competition?
一次书法比赛中，四年级与五年级共有20人获奖，在获奖者中有16人不是四年级的，12人不是五年级的．则这次书法比赛中的获奖总人数是多少人．
<gadget id="calculator">12 - 20</gadget>
<output>-8</output>

<gadget id="calculator">16 + (-8)</gadget>
<output>8</output>

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

<gadget id="calculator">20 + 4</gadget>
<output>24</output>

<result>24</result>