#!/bin/python3

import sys


q = int(input().strip())

for i in range(q):
    n = int(input().strip())
        
    points = []
    xs = []
    ys = []
    
    for j in range(n):
        x,y = input().strip().split(' ')
        x,y = [int(x),int(y)]
        points.append((x, y))
        xs.append(x)
        ys.append(y)
    
    #print(points, xs, ys)
    if n <= 2:
        print('YES')
        continue
    
    min_y = min(ys)
    ys = [y-min_y for y in ys]
    min_x = min(xs)
    #min_x = min([x for x, y in points if y == min_y])
    xs = [x-min_x for x in xs]
    #print(points)
    for k in range(n):
        points[k] = (xs[k], ys[k])
    #print(points)
    
    max_y = max(ys)
    max_x = max(xs)
    count_y = ys.count(max_y)
    count_x = xs.count(max_x)
    
    if (count_y < n and max_y == 0) or (count_x < n and max_x == 0):
        print('NO')
        sys.exit(0)
    
    yes = True
    for x, y in points:
        if (x in [0, max_x] and y in range(max_y + 1)) or (y in [0, max_y] and x in range(max_x + 1)):
            continue
        yes = False
        break
    if yes:
        print('YES')
    else:
        print('NO')