开发一个程序检验密码。一些网站设定了一些制定密码的规则，编写一个方法，检验一个字符串是否是合法的密码。假设密码规则如下：

（1）密码必须至少有8个字符；

（2）密码只能包括字母和数字；

（3）密码必须至少有2个数字

编写一个程序提示用户输入密码，如果该密码符合规则就显示“Valid Password”，否则显示“Invalid Password”-Develop a routine test password. Some websites set some rules for the development of a password, write a method that checks whether a string is valid password. Assuming the password rules are as follows: (1) the password must be at least eight characters　(2) password can only contain letters and numbers　(3) The password must have at least two digits to write a program prompts the user for a password if the password is in line with the rules on the show " Valid Password" , otherwise display " Invalid Password"