#!/usr/bin/env python3
queries = int(input().strip())

def CheckRectangle(points):
    x_list, y_list = [], []
    for x, y in points:
        x_list.append(x)
        y_list.append(y)
    x_min = min(x_list)
    x_max = max(x_list)
    y_min = min(y_list)
    y_max = max(y_list)
    
    for x, y in points:
        if x != x_min and x != x_max:
            if y != y_min and y != y_max:
                return "NO"
        if y != y_min and y != y_max:
            if x != x_min and x != x_max:
                return "NO"
            
    return "YES"
    

for q in range(queries):
    n = int(input().strip())
    points = []
    for i in range(n):
        x, y = list(map(int, input().strip().split()))
        points.append((x,y))
        
    print(CheckRectangle(points))