A school has winter vacation on January 18, and students return to school on February 22. How many days are there in this winter vacation?
某学校1月18日放寒假，2月22日学生返校，这个寒假共有多少天．
<gadget id="calculator">31 - 18</gadget>
<output>13</output>

<gadget id="calculator">22 - 1</gadget>
<output>21</output>

<gadget id="calculator">13 + 1 + 21</gadget>
<output>35</output>

<result>35</result>