q = int(raw_input())

for iq in xrange(q):
	n = int(raw_input())
	pts = []
	xs = []
	ys = []
	for i in xrange(n):
		pt = map(int, raw_input().split())
		pts.append(pt)
		xs.append(pt[0])
		ys.append(pt[1])
	x1 = min(xs)
	x2 = max(xs)
	y1 = min(ys)
	y2 = max(ys)
	on_edges = True
	for pt in pts:
		if not ((pt[0] == x1 and pt[1] >= y1 and pt[1] <= y2) or
				(pt[0] == x2 and pt[1] >= y1 and pt[1] <= y2) or
				(pt[1] == y1 and pt[0] >= x1 and pt[0] <= x2) or
				(pt[1] == y2 and pt[0] >= x1 and pt[0] <= x2)):
			on_edges = False
			break
	print "YES" if on_edges else "NO"