queries = int(input())
for query in range(queries):
	n = int(input())
	xs = []
	ys = []
	points = []
	for p in range(n):
		x, y = map(int, input().split())
		xs.append(x)
		ys.append(y)
		points.append((x, y))

	for p in points:
		if p[0]!= min(xs) and p[0] != max(xs) and p[1]!= min(ys) and p[1] != max(ys):
			print('NO')
			break
	else:
		print('YES')