import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int t = in.nextInt();
        outerloop:
        while (t-- > 0){
            int n = in.nextInt();
            int minx = Integer.MAX_VALUE;
            int maxx = Integer.MIN_VALUE;
            int miny = Integer.MAX_VALUE;
            int maxy = Integer.MIN_VALUE;
            Point[] p = new Point[n];
            for (int i = 0; i < n; i++){
                p[i] = new Point(in.nextInt(), in.nextInt());
                if (minx > p[i].x) minx = p[i].x;
                if (maxx < p[i].x) maxx = p[i].x;
                if (miny > p[i].y) miny = p[i].y;
                if (maxy < p[i].y) maxy = p[i].y;
            }
            for (Point po : p){
                if (po.x != minx && po.x != maxx && po.y != miny && po.y != maxy){
                    System.out.println("NO");
                    continue outerloop;
                }
            }
            System.out.println("YES");
        }
    }
}

class Point{
    public int x;
    public int y;
    
    public Point(int x, int y){
        this.x = x;
        this.y = y;
    }
}