A total of 240 cypress trees were planted along the road from beginning to end. There are two holly trees between every two adjacent cypress trees. How many holly trees are there?
公路的-边从头到尾共栽240棵柏树．每相邻的两棵柏树之间有2棵冬青树．冬青树共有多少棵？
<gadget id="calculator">240 - 1</gadget>
<output>239</output>

<gadget id="calculator">239 * 2</gadget>
<output>478</output>

<result>478</result>