# Enter your code here. Read input from STDIN. Print output to STDOUT
import sys
q = input()
for i in xrange(q):
    n = input()
    lis1 = []
    lis2 = []
    for j in xrange(n):
        x,y = map(int, raw_input().split())
        lis1.append(x)
        lis2.append(y)
    a=max(lis1)
    b=max(lis2)
    c=min(lis1)
    d=min(lis2)
    # print a,b,c,d
    flag = True
    for j in xrange(n):
        if ((lis1[j] not in (a,b,c,d)) and (lis2[j] not in (a,b,c,d))):
            flag = False
            break
    if flag:
        print 'YES'
    else:
        print 'NO'