The students have summer vacation on July 2nd and come to school on September 1st. How many days are there in the summer vacation?
学生7月2日放暑假，9月1日到校上课，暑假共多少天．
<gadget id="calculator">31 - 2</gadget>
<output>29</output>

<gadget id="calculator">29 + 1</gadget>
<output>30</output>

<gadget id="calculator">31 + 30</gadget>
<output>61</output>

<result>61</result>