There are small sticks with a length of 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, and 9 cm. Use some of these small sticks (the sticks cannot be broken) to form a circle. What is the length of the largest square in centimeters?
有长1厘米、2厘米、3厘米、4厘米、5厘米、6厘米、7厘米、8厘米、9厘米的小棒各一根，用其中一些小棒(不能折断小棒)围成一个周长最大的正方形，这个正方形的边长是多少厘米．
<gadget id="calculator">9 + 2</gadget>
<output>11</output>

<result>11</result>