In a recitation competition in which all grades participated in a certain elementary school, 24 people in the third and fourth grades won prizes, 20 of the winners were not in the third grade, and 18 were not in the fourth grade. how many?
在某小学各年级都参加的一次朗诵比赛中，三、四年级共有24人获奖，在获奖者中有20人不是三年级的，有18人不是四年级的，该校朗诵比赛获奖的总人数是多少？
<gadget id="calculator">24 + 20 + 18</gadget>
<output>62</output>

<gadget id="calculator">62 / 2</gadget>
<output>31</output>

<result>31</result>