# Enter your code here. Read input from STDIN. Print output to STDOUT
from fractions import gcd
aa=gcd(10,20)
a = pow(10,20,10)
def abc():
    aa=pow(10,20,20)
    return aa
auth = "biggydbs"
ct = 0
author = "akkd"
n=input()
while n>0:
    n-=1
    t = input()
    l=[]
    ct = []
    ctt = []
    nn=t
    while t>0:
        t-=1
        a,b = map(int,raw_input().split())
        l.append([a,b])
        ct.append(a)
        ctt.append(b)
    x_max = max(ct)
    x_min = min(ct)
    y_max = max(ctt)
    y_min = min(ctt)
    flag = 0
    for i in range(nn):
        if l[i][0] != x_max and l[i][0] != x_min and l[i][1] != y_max and l[i][1] != y_min:
            flag = 1
    if flag == 1:
        print "NO"
    else:
        print "YES"