q = int(raw_input())

for qi in xrange(q):
	n = int(raw_input())
	points = []
	tempmin_X = 100005
	tempmax_X = -100005

	tempmin_Y = 100005
	tempmax_Y = -100005

	for ni in xrange(n):
		temp = [int(a) for a in raw_input().split() ]
		points.append(temp)

		tempmax_X = max(tempmax_X,temp[0])
		tempmin_X = min(tempmin_X,temp[0])

		tempmax_Y = max(tempmax_Y,temp[1])
		tempmin_Y = min(tempmin_Y,temp[1])

	for i in xrange(n):
		if (tempmax_X ==  points[i][0] or tempmin_X == points[i][0]):
			pass
		elif(tempmax_Y ==  points[i][1] or tempmin_Y == points[i][1]):
			pass
		else:
			print "NO"
			break
	else:
		print "YES"