my $range = <RANGES>;
    until( eof( RANGES ) ) {
        my( $start, $end ) = $range =~ m[^$id\t(\d+)\t(\d+)]
            or last;
        my $count = 0;
        vec( $bits, $_, 1 ) and ++$count for $start .. $end;
        print "$id ($1 .. $2) : $count";
        $range = <RANGES>
    }