From March 15th to April 2nd, how many days have passed?
从3月15日到4月2日，一共经过了多少天．
<gadget id="calculator">31 - 15</gadget>
<output>16</output>

<gadget id="calculator">16 + 1 + 2</gadget>
<output>19</output>

<result>19</result>