A series of brackets is complete if we can pair off each left bracket '[' with a right bracket ']' that occurs later in the series. Every bracket must participate in exactly one such pair.
Given a String text add the minimal number of brackets to the beginning and/or end of text to make it complete. Return the result.
|-||text will have between 1 and 50 characters inclusive.|
|-||text will contain only the characters '[' and ']'.|