#!/usr/bin/python
import sys
data = sys.stdin.readlines()
nbcs = int(data[0].strip())
l = 1
for i in range(1, nbcs+1):
    lines = int(data[l].strip())
    tab1 = []
    tab2 = []
    l+=1
    for j in range(1, lines+1):
        tab1.append(int(data[l].strip().split()[0]))
        tab2.append(int(data[l].strip().split()[1]))
        l+=1
    min1, max1 = tab1[0], tab1[0]
    min2, max2 = tab2[0], tab2[0]
    for j in range(0, lines):
        if tab1[j] > max1:
            max1 = tab1[j]
        if tab2[j] > max2:
            max2 = tab2[j]
        if tab1[j] < min1:
            min1 = tab1[j]
        if tab2[j] < min2:
            min2 = tab2[j]
    tt = True
    for j in range(0, lines):
        if (tab1[j] != min1 and tab1[j] != max1) and (tab2[j] != min2 and tab2[j] != max2):
            tt = False
            break
    if tt:
        print ("YES")
    else:
        print("NO")