# Enter your code here. Read input from STDIN. Print output to STDOUT

def degen(x,y):
  max_x = max(x)
  max_y = max(y)
  min_x = min(x)
  min_y = min(y)
  if (max_x == min_x) or (max_y == min_y):
    return 'YES'
  for ix in xrange(len(x)):
    top = y[ix] == max_y
    bottom = y[ix] == min_y
    left = x[ix] == min_x
    right = x[ix] == max_x
    if not(top) and not(bottom) and not(left) and not(right): #
      return 'NO'
  return 'YES'

q = int(raw_input().strip())
for _ in xrange(q):
  n = int(raw_input().strip())
  x, y = [], []
  for ix in xrange(n):
    tx, ty = raw_input().strip().split(' ')
    tx, ty = [int(tx),int(ty)]
    x.append(tx)
    y.append(ty)
  print degen(x,y)