for _q in range(int(input().strip())):
    points = [tuple(map(int,input().strip().split())) for _ in range(int(input().strip()))]
    x0 = min([point[0] for point in points])
    x1 = max([point[0] for point in points])
    y0 = min([point[1] for point in points])
    y1 = max([point[1] for point in points])
    # print(x0,x1,y0,y1)
    # for point in points:
    #  print(point[0] == x0)
    #  print(point[0] == x0 or point[0] == x1 | point[1] == y0 | point[1] == y1)
    # print([(point[0] == x0 | point[0] == x1 | point[1] == y0 | point[1] == y1) for point in points])
    if (all([(point[0] == x0 or point[0] == x1 or point[1] == y0 or point[1] == y1) for point in points])):
        print("YES")
    else:
        print("NO")