There are three kinds of sticks, the lengths are 3 cm, 6 cm and 9 cm. An isosceles triangle can be formed by choosing a small stick of 6 cm and two small sticks of that size.
有三种小棒，长度分别是3厘米、6厘米和9厘米．选一根6厘米的小棒和两根多少厘米的小棒可以围成一个等腰三角形．
<result>9</result>