#!/bin/python3
import sys


Q = int(input())

for q in range(Q):
	N = int(input())

	points = []
	point_count = 0

	minx = float('inf')
	miny = float('inf')
	maxx = float('-inf')
	maxy = float('-inf')

	for i in range(N):
		point = [int(i) for i in input().strip().split()]
		minx = min(minx, point[0])
		maxx = max(maxx, point[0])

		miny = min(miny, point[1])
		maxy = max(maxy, point[1])

		points += [point]
		point_count += 1


	def valid():
		for p in points:
			if p[0] != minx and p[0] != maxx and p[1] != miny and p[1] != maxy:
				return False
		return True

	print('YES' if valid() else 'NO')