The Book Corner of Class 6 and 1 has three types of books: popular science, stories, and pictorials. It is stipulated that each student can borrow at most two of these different types of books. Then, when at least how many students come to borrow books, there must be two students who borrow the same type of books.
六1班图书角有科普、故事和画报三类图书，规定每位同学最多可以借阅其中两类不同的图书．那么，当至少有多少位同学来借阅时就一定会有两位同学借阅图书的种类相同．
<gadget id="calculator">3 + 3</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<result>7</result>