The teacher bought some homework assignments for the students, 2 copies and 2 assignments left 1 copy, 3 assignments and 3 assignments left 1 copy, 5 copies and 5 assignments left 1 copy. How many homework books did the teacher buy at least?
老师买来一些作业本分给同学们，2本2本地分剩l本，3本3本地分也剩1本，5本5本地分也剩1本．老师至少买来多少本作业本？
<gadget id="calculator">2 * 3 * 5</gadget>
<output>30</output>

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

<result>31</result>