The teacher distributes notebooks to the students, 2 books per person and 1 book, 3 books per person and 1 book, 5 books per person, 4 books less. How many books are there at least?
老师给学生们发本子，每人2本余1本，每人3本也余1本，每人5本则少4本．这些本子至少有多少本．
<gadget id="calculator">2 * 3 * 5</gadget>
<output>30</output>

<gadget id="calculator">30 + 1</gadget>
<output>31</output>

<result>31</result>