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 reader = new Scanner(System.in);
		int q = reader.nextInt();
		int n;

		for(int i = 0; i < q; i++){
			n = reader.nextInt();
			ArrayList<Side> sides = new ArrayList<Side>();
			HashMap<Integer, Integer> commonSides = new HashMap<Integer, Integer>();
			for(int x = 0; x < n; x++){
				int sideX = reader.nextInt();
				int sideY = reader.nextInt();
				sides.add(new Side(sideX, sideY));
			}
			
			if(checkSides(sides)){
				System.out.println("YES");
			}else{
				System.out.println("NO");
			}

			//for(Side side: sides){
			//	System.out.println(side.getX()+" "+side.getY());
			//}
			

		}
		
		
	}
	static boolean checkSides(ArrayList<Side> sides){
		int maxX = Integer.MIN_VALUE;
		int maxY = Integer.MIN_VALUE;
		int minX = Integer.MAX_VALUE;
		int minY = Integer.MAX_VALUE;
		for(Side side: sides){
			if(side.getX() > maxX) maxX = side.getX();
			if(side.getX() < minX) minX = side.getX();
			if(side.getY() > maxY) maxY = side.getY();
			if(side.getY() < minY) minY = side.getY();
		}

		//there shouldn't be anything on a point that is not maxx, minx, maxy or miny
		
		for(Side side: sides){
			if(side.getX() != maxX 
					&& side.getX() != minX
					&& side.getY() != maxY 
					&& side.getY() != minY){
				return false;
			}
		}

		return true;
	}
}

	


class Side{
	private int x;
	private int y;
	public Side(int x, int y){
		this.x = x;
		this.y = y;
	}
	
	public int getX(){
		return x;
	}
	
	public int getY(){
		return y;
	}
}