_{NOTE - Forward reference is supported by JGsoft, .NET, Java, Perl, PCRE, PHP, Delphi and Ruby regex flavors.}

Forward reference creates a back reference to a regex that would appear later.
Forward references are only useful if they're inside a repeated group.
Then there may arise a case in which the regex engine evaluates the backreference after the group has been matched already.

Task

You have a test string .
Your task is to write a regex which will match , with following condition(s):

• consists of tic or tac.
• tic should not be immediate neighbour of itself.
• The first tic must occur only when tac has appeared at least twice before.

Valid

tactactic
tactactictactic

Invalid

tactactictactictictac
tactictac

Note

This is a regex only challenge. You are not required to write any code.
You only have to fill the regex pattern in the blank (_________).