Reference - [Treap on neerc.ifmo.ru](https://neerc.ifmo.ru/wiki/index.php?title=%D0%94%D0%B5%D0%BA%D0%B0%D1%80%D1%82%D0%BE%D0%B2%D0%BE_%D0%B4%D0%B5%D1%80%D0%B5%D0%B2%D0%BE)
