There are science books, story books, and art books in the library. Let the students in Class 51 borrow books, they have to borrow them, and they can borrow up to 3 books. To ensure that the content and quantity of books borrowed by 3 students are exactly the same, then how many students are there in Class 51 at least?
图书馆中有科技书、故事书、美术书．让五1班同学去借书，不能不借，最多借3本．要确保有3个同学借书的内容和数量完全一样，那么五1班至少有多少名学生．
<gadget id="calculator">3 + 6 + 10</gadget>
<output>19</output>

<gadget id="calculator">19 * 2</gadget>
<output>38</output>

<gadget id="calculator">38 + 1</gadget>
<output>39</output>

<result>39</result>