# Enter your code here. Read input from STDIN. Print output to STDOUT
q = int(raw_input().strip())
for q1 in range(q):
    n = int(raw_input().strip())
    pts = []
    minx = None
    miny = None
    maxx = None
    maxy = None
    for n1 in range(n):
        x,y = map(int, raw_input().strip().split())
        if maxx == None or x > maxx:
            maxx = x
        if maxy == None or y > maxy:
            maxy = y
        if minx == None or x < minx:
            minx = x
        if miny == None or y < miny:
            miny = y
        pts += [[x,y]]
    nono = False
    for i in pts: 
        x = i[0]
        y = i[1]
        if (y != maxy and y != miny and x != maxx and x != minx):
            print "NO"
            nono = True
            break
    if not nono:
        print "YES"