How many days does Li Sheng participate in the summer camp from July 15th to August 10th?
李胜同学参加暑期夏令营活动，从7月15日到8月10日，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 + 10</gadget>
<output>27</output>

<result>27</result>