q = int(input())

for i in range(q):
    p = int(input())
    ps = []
    minx, miny, maxx, maxy = 100000, 100000, -100000, -100000
    res = 'YES'

    for j in range(p):
        pp = [int(x) for x in input().split()]
        minx = min(minx, pp[0])
        miny = min(miny, pp[1])
        maxx = max(maxx, pp[0])
        maxy = max(maxy, pp[1])
        ps.append(pp)

    for pp in ps:
        if not (pp[0] == maxx or pp[0] == minx or pp[1] == miny or pp[1] == maxy):
            res = 'NO'

    print(res)