q = int(input())

for _ in range(q):
    xs = []
    ys = []
    n = int(input())
    for _ in range(n):
        x,y = [int(elem) for elem in input().split()]
        xs += [x]
        ys += [y]
    if n <= 3:
        print("YES")
    elif n > 3:
        if len(set(xs)) > 2 or len(set(ys)) > 2:
            print("NO")
        else:
            print("YES")