#include <iostream>
#include <utility>
#include <vector>

using namespace std;

bool allOnRectangle(const vector<pair<int,int>> &points);

int main() {
	int queryCount;
	cin >> queryCount;
	for (int i=0; i<queryCount; ++i) {
		int pointCount;
		cin >> pointCount;
		vector<pair<int,int>> points;
		points.reserve(pointCount);
		for (int i=0; i<pointCount; ++i) {
			int x, y;
			cin >> x >> y;
			points.emplace_back(x,y);
		}
		if (allOnRectangle(points)) {
			cout << "YES\n";
		} else {
			cout << "NO\n";
		}
	}
	return 0;
}

bool allOnRectangle(const vector<pair<int,int>> &points) {
	if (points.size() <= 2) {
		//always true here
		return true;
	}
	int minX{points[0].first}, minY{points[0].second};
	int maxX{points[0].first}, maxY{points[0].second};
	for (int i=1; i<points.size(); ++i) {
		int x = points[i].first;
		int y = points[i].second;
		if (x < minX) {
			minX = x;
		} else if (x > maxX) {
			maxX = x;
		}
		if (y < minY) {
			minY = y;
		} else if (y > maxY) {
			maxY = y;
		}
	}
	// cout << "minX " << minX << ", maxX " << maxX << ", minY " << minY << ", maxY " << maxY << '\n';
	for (const auto &xyPoint : points) {
		if (xyPoint.first == maxX || xyPoint.first == minX) {
			//This is always ok
			continue;
		}
		if (xyPoint.second == maxY || xyPoint.second == minY) {
			//This is always ok
			continue;
		}
		return false;
	}
	return true;
}