The forest protection activity started on July 20th and ended on September 3rd. How many days did this activity last?
森林保护活动7月20日开始，9月3日结束，此活动共进行了多少天．
<gadget id="calculator">31 - 20</gadget>
<output>11</output>

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

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">11 + 1 + 30 + 1 + 2 + 1</gadget>
<output>46</output>

<result>46</result>