/
   ^
   (?: .{0,3} | (?!bank}.{4} | .{5,} )
   nova [ ] scotia
   (?: .{0,3} | (?!bank}.{4} | .{5,} )
   $
/sx

##</code><code>##

/
   ^
   (?: | [^b].* | b[^a].* | ba[^n].* | ban[^k].* | bank.+ )
   nova [ ] scotia
   (?: | [^b].* | b[^a].* | ba[^n].* | ban[^k].* | bank.+ )
   $
/sx

##</code><code>##

/
   ^
   (?: (?!bank). )*
   nova [ ] scotia
   (?: (?!bank). )*
   $
/sx