#include <algorithm>
#include <array>
#include <chrono>
#include <climits>
#include <cmath>
#include <cstdlib>
#include <deque>
#include <forward_list>
#include <functional>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <regex>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <valarray>
#include <vector>

using namespace std;

struct Pos
{
	int x;
	int y;
};

bool checkOnRect(const vector<Pos>& points)
{
	int minX = INT_MAX, minY = INT_MAX, maxX = INT_MIN, maxY = INT_MIN;
	for (const Pos& point : points)
	{
		if (point.x < minX)
			minX = point.x;
		if (point.y < minY)
			minY = point.y;
		if (point.x > maxX)
			maxX = point.x;
		if (point.y > maxY)
			maxY = point.y;
	}

	//if (maxX == minX || maxY == minY)
	//	return false;

	for (const Pos& p : points)
	{
		if (p.x != minX && p.x != maxX && p.y != maxY && p.y != minY)
			return false;
	}
	return true;
}

int main()
{
	ios::sync_with_stdio(false);

	int Q;
	cin >> Q;
	for (int q = 0; q < Q; q++)
	{
		int n; 
		cin >> n;

		vector<Pos> points(n);
		for (int i = 0; i < n; i++)
		{
			cin >> points[i].x >> points[i].y;
		}
		bool onRect = checkOnRect(points);
		if (onRect)
			cout << "YES" << endl;
		else
			cout << "NO" << endl;
	}

	return 0;
}