q = int(input())
for _ in range(q):
    n = int(input())
    poi = []
    maxx = maxy = -100000
    minx = miny = 100000
    for _ in range(n):
        x, y = map(int, input().split())
        poi.append((x, y))
        if x > maxx:
            maxx = x
        if x < minx:
            minx = x
        if y > maxy:
            maxy = y
        if y < miny:
            miny = y
    
    flag = 1
    for p in poi:
        if p[0] == maxx or p[0] == minx or p[1] == maxy or p[1] == miny:
            continue
        else:
            flag = 0
            break
            
    
    if flag == 1:
        print('YES')
    else:
        print('NO')