The temperature in a certain city on December 19, 2012 is -13°C ~ 2°C, what is the temperature difference in the city on this day?
某市2012年12月19日的气温是-13℃～2℃，这一天该市的温差是多少℃．
<gadget id="calculator">2 - (-13)</gadget>
<output>15</output>

<result>15</result>