# Enter your code here. Read input from STDIN. Print output to STDOUT
import sys
q = int(raw_input())

def not_in(v, corner_min, corner_max):
    return v != corner_min and v != corner_max

for query in xrange(q):
    n = int(raw_input())
    corner_l = sys.maxint
    corner_r = -sys.maxint
    corner_u = -sys.maxint
    corner_b = sys.maxint
    
    points = []
    for point in xrange(n):
        x, y = [int(v) for v in raw_input().split()]
        points.append((x, y))
        corner_l = min(x, corner_l)
        corner_r = max(x, corner_r)
        corner_u = max(y, corner_u)
        corner_b = min(y, corner_b)
    
    if any([not_in(x, corner_l, corner_r) and not_in(y, corner_u, corner_b)
            for x, y in points]):
        print 'NO'
    else:
        print 'YES'