There is a method of expressing the date with six digits, such as: 890817 means August 17, 1989, that is, from left to right, the first and second digits represent the year, the third and fourth digits represent the month, and the fifth and sixth digits represent the month. The digits represent the day. If the date of 1991 is expressed in this way, how many days are there in the whole year with six different numbers?
有一种用六位数表示日期的方法，如：890817表示的是1989年8月17日，也就是从左到右第一、二位表示年，第三、四位表示月，第五、六位表示日．如果用这种方法表示1991年的日期，那么全年中六个数字都不相同的日期有多少天．
<gadget id="calculator">6 * 5</gadget>
<output>30</output>

<result>30</result>