test = input()
while test:
	queries = input()
	input_points = []


	for x in xrange(0,queries):
		x,y = map(int, raw_input().split())
		input_points.append((x,y))

	min_x = input_points[0][0]
	min_y = input_points[0][1]
	max_x = input_points[0][0]
	max_y = input_points[0][1]

	for x in xrange(1, len(input_points)):
		if (input_points[x][0] < min_x):
			min_x = input_points[x][0]
		if (input_points[x][1] < min_y):
			min_y = input_points[x][1]

		if (input_points[x][0] > max_x):
			max_x = input_points[x][0]

		if (input_points[x][1] > max_y):
			max_y = input_points[x][1]

	isInside = False
	for x in input_points:
		if (x[0] > min_x and x[1] > min_y and x[0] < max_x and x[1] < max_y):
			isInside = True

	if isInside == True:
		print('NO')
	else:
		print('YES')
	test -=1