Person first name should accept capsinit format else it should through error

Summary:

The business requirement is to put some validation on the name entered format. The name field should accept only capsinit values(EX: Steve Smith), and it should through an error when all the letters in the name capital(EX: STEVE SMITH) also it should through an error when all the letters are small(EX: steve smith)

Let us know how can we achieve this.

Content (required):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):