An administrator forgot the password number of his small safe, and only remembered that it was composed of 3 non-zero and different numbers, and the sum of these 3 numbers was 9. What is the maximum number of attempts to make sure the safe is opened?
某管理员忘了自己小保险柜的密码数字，只记得是由：3个非零的且互不相同的数字组成，且这3个数字的和是9．为确保打开保险柜，至多要试多少次？
<gadget id="calculator">6 + 6 + 6</gadget>
<output>18</output>

<result>18</result>