# Enter your code here. Read input from STDIN. Print output to STDOUTs
from collections import defaultdict
q=int(raw_input())
for i in range(q):
    pointsx=defaultdict(int)
    pointsy=defaultdict(int)
    points=[]
    n=int(raw_input())
    for j in range(n): 
        p=map(int,raw_input().split())
        points.append(p)
    minx=min([x[0] for x in points])
    maxx=max([x[0] for x in points])
    miny=min([x[1] for x in points])
    maxy=max([x[1] for x in points])
    check=0
    for p in points:
        if not (p[0]==minx or p[0]==maxx or p[1]==miny or p[1]==maxy): check=1
 
    if check: print 'NO'
    else: print 'YES'