for (my $i = 0; $i < @range; $i++) {
REDO:
    my $e = $range[$i][1];
    for(my $j = $i+1; $j < @range; $j++) {
        unless($range[$j][0] > $e) {
            $range[$i][1] = $range[$j][1] if $range[$j][1] > $e;
            splice @range, $j, 1;
            goto REDO;
        }
    }
}