sub sorted_descending {
    my $arr = shift;
    for (my $i = 0; $i < scalar(@$arr) - 1; $i++) {
        return 0 if ($arr->[$i] lt $arr->[$i + 1]);
    }
    return 1;
}

sub biggerIsGreater {
    my $w = shift;
    
    my @arr = split("", $w);
    my $max = $arr[1];
    my $ind = 0;
    my @res;
    if (sorted_descending(\@arr)) {
        return "no answer";
    } else {
        my $k = $#arr - 1;
        while ($k >= 0 && $arr[$k] ge $arr[$k + 1]) {
            $k--;
        }
        
        my $l = $#arr; 
        while ($arr[$l] le $arr[$k]) {
            $l--;
        }
        
        ($arr[$k], $arr[$l]) = ($arr[$l], $arr[$k]);
        push(@res, @arr[0..$k], reverse(splice(@arr, $k+1, $#arr)));
        
        return join("", @res);
    }
}