my %lookup = map { $_ => 1 << (ord($_) - ord('A')) } 'A'..'Z';

my $c = 'ABCHI';

my $bitmap = 0;
$bitmap |= $lookup{$_} for $c =~ /(.)/g;

print('A'..'Z', "\n");
print(scalar(reverse(sprintf("%26b", $bitmap))), "\n");