This year's summer vacation starts on July 14th and ends on August 19th. How many days are there in total?
今年的暑假从7月14日开始，8月19日结束，假期共多少天．
<gadget id="calculator">31 - 14</gadget>
<output>17</output>

<gadget id="calculator">17 + 1</gadget>
<output>18</output>

<gadget id="calculator">18 + 19</gadget>
<output>37</output>

<result>37</result>