From July 27 to August 12, 2012, the 30th Summer Olympic Games was held in London. Is this a normal year or a leap year? How many days did the Olympic Games last?
2012年7月27日至8月12日，第30届夏季奥运会在伦敦举行．这一年是平年还是闰年？这届奥运会共历时多少天？
<gadget id="calculator">31 - 27</gadget>
<output>4</output>

<gadget id="calculator">4 + 1 + 12</gadget>
<output>17</output>

<result>17</result>