Rule for moving based on word in subject

I need to create a rule to move emails from my INBOX to JUNK EMAIL based on the subject.  I have started getting a lot of junk spam that all use a single word in the subject:  “hi”.  I need to create a rule that not only can check for that word (that part I can do) but also will make sure that is the ONLY word in the subject.  For example, if I create a rule to move messages based on “hi” in the subject, it will remove the spam - but it will also remove email with the words “high school” or “highlight” or “hieroglyphics” in the subject.  I want the rule to work ONLY if there is one word in the subject and if that one word is “hi”.  Can this be done?  Thanks!

Hi Steve,
unfortunately this cannot be done.

Best regards,