avoid duplicate

#include <iostream>
#include <set>
#include <queue>
#include <iterator>


class RottenApple

{
public:
	int x;
	int y;

	RottenApple(int x, int y)
	{
		this->x = x;
		this->y = y;
	}

	bool operator ==(const RottenApple& obj) const
	{
		if (this->x == obj.x && this->y == obj.y)
			return true;

		return false;
	}


	void print()
	{
		std::cout << this->x << " " << this->y << std::endl;
	}
};

bool operator<(const RottenApple& a, const RottenApple& b) {
	return a.x < b.x;
}

int main()
{
	int row, column, days;
	std::cin >> row >> column >> days;

	std::set<RottenApple* > rotten_apples;
	std::queue<RottenApple*> queued_apples;

	int x, y;
	while (std::cin >> x >> y)
	{
		RottenApple* apple = new RottenApple(row - x, y - 1);
		queued_apples.push(apple);
	}

	for (int i = 0; i <= days; i++)
	{
		std::queue<RottenApple* > nextInLine;
		while (!queued_apples.empty())
		{
			RottenApple* apple = queued_apples.front();
			queued_apples.pop();
			rotten_apples.insert(apple);

			if (apple->x + 1 < row)
			{
				nextInLine.push(new RottenApple(apple->x + 1, apple->y));
			}

			if (apple->x - 1 >= 0)
			{
				nextInLine.push(new RottenApple(apple->x - 1, apple->y));
			}

			if (apple->y + 1 < column)
			{
				nextInLine.push(new RottenApple(apple->x, apple->y + 1));
			}

			if (apple->y - 1 >= 0)
			{
				nextInLine.push(new RottenApple(apple->x, apple->y - 1));
			}

		}
		queued_apples = nextInLine;
	}


	for (auto temp : rotten_apples)
		temp->print();

	std::cout << rotten_apples.size() << std::endl;

	return 0;
}