# Enter your code here. Read input from STDIN. Print output to STDOUT

def isOnSq(ptList):
    xMin = ptList[0][0]
    xMax = ptList[0][0]
    yMin = ptList[0][1]
    yMax = ptList[0][1]
    result = True
    response = "YES"
    for pt in ptList:
        x,y = pt
        if x < xMin:
            xMin = x
        if x > xMax:
            xMax = x
        if y < yMin:
            yMin = y
        if y > yMax:
            yMax = y
    for pt in ptList:
        x,y = pt
        if x != xMin and x != xMax and y != yMin and y != yMax:
            result = False
            break
    if not result:
        response = "NO"
    return response
            
    
    
Q = int(raw_input())
for qi in xrange(Q):
    N = int(raw_input())
    pts = []
    for pti in xrange(N):
        x,y = [int(i) for i in raw_input().split()]
        pts.append((x,y))
    print(isOnSq(pts))