# find line perpendicular or parallel to first line

def find_corner_points(points):
    et, eb, el, er = -10**4, 10**4, -10**4, 10**4
    for p in points:
        #print et, eb, el, er
        if(p[0]>el):
            pl = p
            el = p[0]
        if(p[0]<er):
            pr = p
            er = p[0]
        if(p[1]>et):
            pt = p
            et = p[1]
        if(p[1]<eb):
            pb = p
            eb = p[1]
    #print "ret", et, eb, el, er
    return et, eb, el, er

def on_rect(points):
    if(len(points)<=3):
        return True
    et, eb, el, er = find_corner_points(points)
    #print et, eb, el, er
    flag = 0
    deg = 0
    if(et == eb or el == er):
        deg=1
    for p in points:
        if(not (p[0] == el or p[0]==er or p[1]==et or p[1]==eb)):
            flag =1
            break
    if(flag==1 and deg==0):
        return False
    else:
        return True
          

q = int(raw_input().strip())
for a0 in xrange(q):
    n = int(raw_input().strip())
    points = []
    for a1 in xrange(n):
        x, y = map(int, raw_input().strip().split())
        points.append((x, y))
    if(on_rect(points)):
        print "YES"
    else:
        print "NO"