48 young pioneers select the captain, the candidates are A, B, and C, and the votes are accumulated in the middle of the billing. A gets 13 votes, B gets 10 votes, and C gets 7 votes. If the person with the most votes is elected, then A must get at least how many more votes to be elected.
48名少先队员选中队长，候选人是甲、乙、丙三人，开票中途累计．甲得13票，乙得10票，丙得7票．得票多的人当选，则以后甲至少要再得多少票才能当选．
<gadget id="calculator">13 + 10 + 7</gadget>
<output>30</output>

<gadget id="calculator">48 - 30</gadget>
<output>18</output>

<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<result>8</result>