import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner s = new Scanner(System.in);
        int times = s.nextInt();
        ArrayList<Point> p = new ArrayList<Point>();
        for(int i = 0; i < times; i++){
            int points = s.nextInt();
            for(int j = 0; j < points; j++){
                p.add(new Point(s.nextInt(),s.nextInt()));
            }
            int l = 0;
            int b = 0;
            int ll = 0;
            int lb = 0;
            for(Point point:p){
                if(point.x > l){
                    l = point.x;
                }
                if(point.x < ll){
                    ll = point.x;
                }
                if(point.y > b){
                    b = point.y;
                }
                if(point.y < lb){
                    lb = point.y;
                }
            }
            boolean ans = true;
            for(Point point:p){
                if(point.x == l || point.y == b || point.x == ll || point.y == lb){
                    
                }
                else{
                    ans = false;
                    
                }
                
            }
            if(ans){
                System.out.println("YES");
            }
            else{
                System.out.println("NO");
            }
        }
    }
}
class Point{
    int x; 
    int y;
    Point(int X, int Y){
        x = X;
        y = Y;
    }
}