#!/usr/bin/env python
# -*- coding: utf-8 -*-

if __name__ == "__main__":
    q = int(input())
    for _ in range(q):
        t = int(input())
        points = []
        for __ in range(t):
            a, b = [int(x) for x in input().split()]
            points.append((a, b))
        x_min = min([a for (a, b) in points])
        x_max = max([a for (a, b) in points])
        y_min = min([b for (a, b) in points])
        y_max = max([b for (a, b) in points])
        for a, b in points:
            if a in [x_min, x_max] and y_min <= b <= y_max:
                continue
            if b in [y_min, y_max] and x_min <= a <= x_max:
                continue
            print("NO")
            break
        else:
            print("YES")