The school has three extracurricular activity groups: reading aloud, music, and calligraphy. Each student can join at most two interest groups (or not). At least how many students are there to ensure that no less than 6 students participate in the same situation with small interests.
学校开办有朗读、音乐、书法三个课外活动小组，每个学生最多可以参加两个兴趣小组(可以不参加)．至少有多少名学生，才能保证不少于6名学生参加兴趣小的情况完全相同．
<gadget id="calculator">1 + 3 + 3</gadget>
<output>7</output>

<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">7 * 5</gadget>
<output>35</output>

<gadget id="calculator">35 + 1</gadget>
<output>36</output>

<result>36</result>