Windows Server 2008 initial login password modification skills

Today installed a Windows
Server 2008 Enterprise Edition, when prompted to change the password when entering the system for the first time, so I randomly entered the content, but the old Prompt error, said the password does not meet the requirements, tried many times and finally found the skills, to share.

The password must be eight or more digits combined with uppercase and lowercase letters and numbers, that is, at least three different characters in the password, such as Windows2008. Where W is the size of the letter, indows are lowercase letters, 2008 is a number, there are exactly three different characters.