Lan Lan left for the summer camp on the morning of July 15th, and returned home in the afternoon on the 9th of next month. How many days does the summer camp last?
兰兰7月15日早上出发去参加夏令营，到下个月9日下午结束回家，夏令营一共有多少天？
<gadget id="calculator">31 - 15</gadget>
<output>16</output>

<gadget id="calculator">16 + 1</gadget>
<output>17</output>

<gadget id="calculator">17 + 9</gadget>
<output>26</output>

<result>26</result>