Q = int(input())
for q in range(Q):
    N = int(input())
    a = []
    maxX = 0
    minX = 0
    maxY = 0
    minY = 0
    for n in range(N):
        t = list(map(int, input().split()))
        if n == 0:
            minX = t[0]
            maxX = t[0]
            minY = t[1]
            maxY = t[1]
        a.append(t)
        if t[1] > maxY:
            maxY = t[1]
        if t[1] < minY:
            minY = t[1]
        if t[0] > maxX:
            maxX = t[0]
        if t[0] < minX:
            minX = t[0]
    r = True
    for i in a:  
        f = False
        if i[0] >= minX and i[0] <= maxX and i[1] == minY:
            f = True
        if i[0] >= minX and i[0] <= maxX and i[1] == maxY:
            f = True
        if i[1] >= minY and i[1] <= maxY and i[0] == minX:
            f = True
        if i[1] >= minY and i[1] <= maxY and i[0] == maxX:
            f = True
        if not f:
            r = False
            break     
    if maxX == minX:
        r = False
    if minY == maxY:
        r = False   
    if r:
        print("YES")
    else:
        print("NO")