There are one line segment with lengths of 1, 2, 3, 4, 5, 6, 7, 8, and 9 respectively, and several lines are selected to form a square. How many different selection methods are there?
在长度分别为1，2，3，4，5，6，7，8，9的线段各1条，从中选出若干条组成正方形，那么不同的选法有多少种．
<gadget id="calculator">1 + 8</gadget>
<output>9</output>

<result>9</result>