Johny has to create many mailboxes. He knows all of the email addresses, but forgot all the passwords; But Johny remembers that he hides his passwords within the email address and can be revealed using the following steps:

1)all symbols after @ must be removed

2)register of all leters must be changed(uppercase goes to lower and vise versa)

3)all digits must be moved to the front of the password

Your work is to help Johny recover all his passwords!

Example ----> Pass("1johny2@mail.ru")=="12JOHNY"

Note: if mail is empty return null

The test case, while easy to understand, has some english translation errors. I will comment on this with suggested edits.

Otherwise, this is ready.

Looking at the discussion, clearly this kata is doable for some people. Unfortunately, I can't wrap my head around the description and that's completely preventing me from understanding the kata.

I would offer suggestions (as the author asks for in the discussion) but I really don't understand it well enough to do so.