#include <string>
#include <cstdlib>
#include <utility>

using std::string;
typedef unsigned long long count_type;
#define RAND_MAX (1 << 62)
class line;
typedef std::pair<line*, line*> two_lines;

// Treap node representation of a line
struct line {
	count_type priority, size;
	string text;
	line *left, *right;

	line(count_type _p, string _t) : priority(_p), text(_t), size(-1), left(nullptr), right(nullptr) {}
};

// Treap representation of a file
class file {
	line* root;

	file() {
		srand(120);
		root = nullptr;
	}

	// Split treap by k-th element
	// TODO with sizes
	two_lines split(line *l, count_type k) {
		if(l == nullptr) return {nullptr, nullptr};

		if(l->size <= k) {
			auto two = split(l->right, k);
			l->right = two.first;
			return {l, two.second};
		}
		else {
			auto two = split(l->left, k - 1 - (l->left == nullptr ? 0 : l->left->size));
			l->left = two.second;
			return {two.first, l};
		}
	}
	// Join two treaps
	// TODO with sizes
	line* join(line *a, line *b) {
		if(a == nullptr) return b;
		if(b == nullptr) return a;

		if(a->priority < b->priority) {
			a->right = join(a->right, b);
			return a;
		}
		else {
			b->left = join(a, b->left);
			return b;
		}
	}
	line* join(two_lines two) { return join(two.first, two.second); }

public:
	line* find(line* l, count_type k) {
		if(l == nullptr) return nullptr;

		if(k < l->size)
			return find(l->left, k);
		else if(k > l->size)
			return find(l->right, k - 1 - (l->left == nullptr ? 0 : l->left->size) );
		else
			return l;
	}
	void insert(int k, string s) {
		line *l = new line(rand(), s);

		if(root == nullptr) {
			root = l;
			return;
		}

		auto two = split(root, k);
		join(two.first, l);
		join(two);
	}
	void remove(count_type k) {
		auto two = split(root, k);
		two.first = split(two.first, k-1).first;
		join(two);
	}
};