Q = int(input())
for _ in range(Q):
    N = int(input())
    L = []
    for _ in range(N):
        x, y = [int(n) for n in input().split()]
        L.append((x,y))
    top = max(y for x,y in L)
    bot = min(y for x,y in L)
    left = min(x for x,y in L)
    right = max(x for x,y in L)

    bad = False
    for x, y in L:
        if x == left or x == right:
            if y > top and y < top:
                bad = True
        elif y == top or y == bot:
            if x < left or x > right:
                bad = True
        else:
            bad = True
    print('NO' if bad else 'YES')