The school's 1,200 young pioneers were elected as the captain, and the candidates were A, B, and C. During the election, each person can only vote for one person. Accumulated in the middle of billing, among the first 900 ballots, A gets 420, B gets 250, and C gets 230. If there are no abstentions and invalid votes in this election, the person with the most votes will be elected. Then, among the votes that have not been counted, how many votes A can get at least to be elected.
校1200名少先队员选大队长，候选人是甲乙丙三人．选举时，每人只能投票选举一人．开票中途累计，前900张选票中，甲得420张，乙得250张，丙得230张．如果这次选举没有弃权票，也没有废票，得票最多的1人当选．那么，在尚未统计的选票中，甲至少得多少张就能当选．
<gadget id="calculator">1_200 - 900</gadget>
<output>300</output>

<gadget id="calculator">300 / 2</gadget>
<output>150</output>

<gadget id="calculator">150 - 85</gadget>
<output>65</output>

<gadget id="calculator">65 + 1</gadget>
<output>66</output>

<result>66</result>