<>;
while(<>){

chomp;
@m = split/ /;
#    print"@m\n";

@eil = ();
@mas = ();

sub make{
 #   print ": (@_)\n";
    for (0..@_-1){
 #       print " $_ ::\n";
        my @a = @_;
        $p = splice(@a,$_,1);
  #          print" $p\n";
  #          print " :: (@a)\n";
        push @eil, $p;
        @a and make(@a);
        if (!@a){
  #          print " \@eil : @eil\n";
   #         print "@eil\n";
            $e = join"",@eil;
            splice (@mas,@mas,0,$e);
            } 
        pop @eil;
   #     print " ::: (@a)\n";
        }
    }
    
make(@m);
# print "@mas\n";

$max = undef;
for (@mas){
    $diff = $_ - reverse $_ ;
 #   print "$diff\n";
    defined $max or $max = $diff;
    $diff > $max and $max = $diff;
  #  print "$max\n";
    
    }
    print "$max\n";
}