# Enter your code here. Read input from STDIN. Print output to STDOUT
query=int(raw_input())
for _ in xrange(query):
    p = int(raw_input())
    xs=[]
    ys=[]
    for _ in xrange(p):
        tmp=[int(x) for x in raw_input().split(' ')]
        xs.append(tmp[0])
        ys.append(tmp[1])
    if len(set(xs))<=2 or len(set(ys))<=2:
        print('YES')
    else:
        print('NO')