for _ in xrange(input()):
    minx = miny = 1e5
    maxx = maxy = -1e5
    pts = []
    for _ in xrange(input()):
        x, y = map(int, raw_input().split())
        pts.append((x, y))
        minx = min(minx, x)
        miny = min(miny, y)
        maxx = max(maxx, x)
        maxy = max(maxy, y)
    for x, y in pts:
        if x != minx and x != maxx and y != miny and y != maxy:
            print "NO"
            break
    else:
        print "YES"