Task:

 Generate a string with   N   opening brackets   [   and with   N   closing brackets   ],   in some arbitrary order. 
 Determine whether the generated string is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.


Examples

   (empty)      OK
   []           OK   
   [][]         OK   
   [[][]]       OK 
   ][         NOT OK
   ][][       NOT OK
   []][[]     NOT OK



v                > "KO TON" ,,,,,,   v
> ~ : 25*- #v_ $ |                   > 25*, @
                 > "KO" ,,           ^
            > : 1991+*+- #v_ v
                          > \ : 1991+*+- #v_v
                                          \ $
^                            <            <$<