The Pinggu International Peach Blossom Music Festival will be held from April 17th to May 7th. How many days will the Pinggu Peach Blossom Festival last?
平谷国际桃花音乐节将于4月17日到5月7日，平谷桃花节为期多少天．
<gadget id="calculator">30 - 17</gadget>
<output>13</output>

<gadget id="calculator">13 + 1 + 7</gadget>
<output>21</output>

<result>21</result>