Q = int(input())

def calc(points):
    min_x = max_x = points[0][0]
    min_y = max_y = points[0][1]
    for pt in points[1:]:
        if pt[0] < min_x:
            min_x = pt[0]
        if pt[0] > max_x:
            max_x = pt[0]
        if pt[1] < min_y:
            min_y = pt[1]
        if pt[1] > max_y:
            max_y = pt[1]
          
    for pt in points:
        if min_y < pt[1] < max_y and min_x < pt[0] < max_x:
            return False
        if min_x < pt[0] < max_x and min_y < pt[1] < max_y:
            return False
    return True

for i in range(Q):
    cnt = int(input())
    points = [tuple(map(int, input().split())) for i in range(cnt)]
    print('YES' if calc(points) else 'NO')