Guangming Elementary School will be on winter vacation from January 18th, and the new semester will start on February 9th. How many days are there in winter vacation?
光明小学从1月18日起放寒假，2月9日新学期开学上课．寒假一共有多少天．
<gadget id="calculator">31 - 18</gadget>
<output>13</output>

<gadget id="calculator">13 + 1 + 18</gadget>
<output>32</output>

<result>32</result>