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

public class Solution {

    public static void main(String[] args) {
       Scanner sc = new Scanner(System.in);
        int q = sc.nextInt();
        for(int i=0;i<q ;i++){
            int n = sc.nextInt();
            List<Integer> x = new ArrayList<Integer>();
            List<Integer> y = new ArrayList<Integer>();
            int point[][] = new int[n][2];
            for(int j=0;j<n;j++){
            	int xx=sc.nextInt();
            	int yy = sc.nextInt();
                x.add(xx);
                y.add(yy);
                point[j][0]=xx;
                point[j][1]=yy;
            }
            int maxx=Collections.max(x);
            int minx=Collections.min(x);
            int maxy=Collections.max(y);
            int miny=Collections.min(y);
            boolean yes = true;
            for(int j=0;j<n;j++){
            	if(point[j][0]!=maxx){
            		if(point[j][0]!=minx)
            		if(point[j][1]!=maxy){
            			if(point[j][1]!=miny)
            				yes=false;
            		}
            	}
            }
            if(yes)
            	System.out.println("YES");
            else
            	System.out.println("NO");
            
        }
    }
}