'''input
2
3
0 0
0 1
1 0
4
0 0
0 2
2 0
1 1
'''

def rints():
    return list(map(int, input().split()))

def ri():
    return int(input())

class Point(object):
    def __init__(self, x, y):
        self.x = x
        self.y = y
    def __repr__(self):
        return "Point(%d, %d)" % (self.x, self. y)

def solve(n, points):
    min_x, max_x = min(points, key = lambda p : p.x).x, max(points, key = lambda p : p.x).x
    min_y, max_y = min(points, key = lambda p : p.y).y, max(points, key = lambda p : p.y).y
    # print(min_x, max_x)
    # print(min_y, max_y)
    for p in points:
        if p.x not in (min_x, max_x):
            if p.y not in (min_y, max_y):
                return "NO"
    return "YES"


def main():
    t = ri()
    for _ in range(t):
        n = ri()
        points = [Point(*rints()) for _ in range(n)]
        # print(n, points)
        print(solve(n, points))

main()