In the conference room, there are 5 class cadres from grades 1 to 6 each. If a teacher who is not familiar with these students wants to call out there must be 2 students of the same grade, the minimum number of people to call out.
会议室里坐着1至6年级的班干部各5人，一位不熟悉这些学生的老师要想喊出的人一定有2名同年级的学生，最少要喊出多少人．
<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<result>7</result>