# Enter your code here. Read input from STDIN. Print output to STDOUT
q=int(raw_input())
for iCase in xrange(q):
  n=int(raw_input())
  setx=set([])
  sety=set([])
  points=[]
  for i in xrange(n):
    a,b=map(int,raw_input().split())
    points.append((a,b))
    setx.add(a)
    sety.add(b)
  minx=min(setx)
  maxx=max(setx)
  miny=min(sety)
  maxy=max(sety)
  isOK=True
  for (a,b) in points:
    if minx<a<maxx and miny<b<maxy:
      isOK=False
      break
  print "YES" if isOK else "NO"