q = int(input())

x = []
y =[]

for _ in range(q):
    n = int(input())
    for _ in range(n):
        a,b = [int(x) for x in input().split(" ")]
        x.append(a)
        y.append(b)
    
    if len(set(x)) <= 2 and len(set(y)) <= 2:
        print("YES")
    else:
        print("NO")