#include <iostream>
#include <list>

class Ichien {
	int x;
	int y;
public:
	Ichien(int x, int y) : x(x), y(y) {};
	bool kasanaru(Ichien *other) {
		int x_diff = this->x - other->x;
		int y_diff = this->y - other->y;
		return x_diff * x_diff + y_diff * y_diff < 400;
	}
};

int main() {
	int n;
	int x, y;
	Ichien *ichi;
	std::list<Ichien *> list[21][21];
	std::list<Ichien *> senjo;

	std::cin >> n;
	for (int i = 0; i < n; ++i) {
		std::cin >> x >> y;
		ichi = new Ichien(x, y);
		bool okeru = true;
		for (auto other: list[x/100][y/100]) {
			if (ichi->kasanaru(other)) {
				okeru = false;
				break;
			}
		}
		if (okeru && (x % 100 < 10 || x % 100 > 90 ||
				y % 100 < 10 || y % 100 > 90)) {
			for (auto other: senjo) {
				if (ichi->kasanaru(other)) {
					okeru = false;
					break;
				}
			}
		}
		if (okeru) {
			list[x/100][y/100].push_back(ichi);
			if (x % 100 < 10 || x % 100 > 90 ||
					y % 100 < 10 || y % 100 > 90) {
				senjo.push_back(ichi);
			}
		} else {
			delete ichi;
		}
	}
	int sum = 0;
	for (auto &l: list) {
		for (auto &m: l) {
			sum += m.size();
		}
	}
	std::cout << sum << std::endl;
	return 0;
}