from itertools import chain
q = int(input())
for iter1 in range(q):
    ans = True
    n = int(input())
    a = [tuple(map(int,input().split())) for i in range(n)]
    '''if n < 4:
        print('YES')
        continue'''
    x = [t[0] for t in a]
    y = [t[1] for t in a]
    xmin = min(x)
    xmax = max(x)
    ymin = min(y)
    ymax = max(y)
    for p,q in a:
        if (p != xmin and p != xmax) and (q != ymin and q != ymax):
            print('NO')
            ans = False
            break
    if ans: print('YES')