#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
	/* Enter your code here. Read input from STDIN. Print output to STDOUT */
	int q;	// Number of queries
	cin >> q;
	for (int thisQ = 1; thisQ <= q; thisQ++) {
		int n;	// Number of points >= 1
		cin >> n;
		// Rectangle boundaries;
		int minX, minY;
		int maxX, maxY;
		vector<int> pointX(n), pointY(n);
		bool stillGood = true;

		cin >> pointX[0] >> pointY[0];
		minX = pointX[0];
		maxX = minX;
		minY = pointY[0];
		maxY = minY;

		// Find the rectangle boundaries.
		for (int thisPoint = 1; thisPoint < n; thisPoint++) {
			cin >> pointX[thisPoint] >> pointY[thisPoint];
			if (pointX[thisPoint] < minX)
				minX = pointX[thisPoint];
			else if (pointX[thisPoint] > maxX)
				maxX = pointX[thisPoint];
			if (pointY[thisPoint] < minY)
				minY = pointY[thisPoint];
			else if (pointY[thisPoint] > maxY)
				maxY = pointY[thisPoint];
		}

		// Check that all points are on a boundary.
		for (int thisPoint = 0; thisPoint < n; thisPoint++) {
			if ((pointX[thisPoint] != minX) &&
				(pointX[thisPoint] != maxX) &&
				(pointY[thisPoint] != minY) &&
				(pointY[thisPoint] != maxY)) {
				stillGood = false;
				break;
			}
		}
		
		if (stillGood)
			cout << "YES\n";
		else
			cout << "NO\n";
	}

	return 0;
}