import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.*;
class Points{
	int x,y;
	Points(int a,int b){
		x=a;
		y=b;
	}
}
public class Pro1 {
	static int N;
	static Points array[];
    public static void main(String args[] ) throws Exception {
    	BufferedReader scan = new BufferedReader(new InputStreamReader(System.in));
    	int q  = Integer.parseInt(scan.readLine());
    	label:for(int i=0;i<q;i++){
    		N = Integer.parseInt(scan.readLine());
    		array = new Points[N];
    		for(int j=0;j<N;j++){
    			String input[] = scan.readLine().split(" ");
    			array[j] = new Points(Integer.parseInt(input[0]),Integer.parseInt(input[1]));
    		}
    		arrange();
    		int min_x = array[0].x;
    		int max_x = array[N-1].x;
    		int min_y = 100000;
    		int max_y = -100000;
    		int start = 0;
    		while(array[start].x == min_x){
    			if(min_y>array[start].y)
    				min_y = array[start].y;
    			if(max_y<array[start].y)
    				max_y=array[start].y;
    			start++;
    		}
    		int end = N-1;
    		while(array[end].x == max_x){
    			if(min_y>array[start].y)
    				min_y = array[start].y;
    			if(max_y<array[start].y)
    				max_y=array[start].y;
    			end--;
    		}
    		Set<Integer> ys = new HashSet<Integer>();
    		for(int in=start;in<=end;in++){
    			if(array[in].y>min_y && array[in].y<max_y){
    				System.out.println("NO");
    				continue label;
    			}
    			ys.add(array[in].y);
    		}
    		if(ys.size()<=2)
    			System.out.println("YES");
    		else
    			System.out.println("NO");
    	}
    }
    public static void arrange(){
    	for(int i=0;i<N;i++){
    		int temp=i;
    		while(temp>0 && array[temp].x<array[temp-1].x){
    			Points t = array[temp];
    			array[temp] = array[temp-1];
    			array[temp-1] = t;
    			temp--;
    		}
    		while(temp>0 && array[temp].y<array[temp-1].y && array[temp].x==array[temp-1].x){
    			Points t = array[temp];
    			array[temp] = array[temp-1];
    			array[temp-1] = t;
    			temp--;
    		}
    	}
    }
}