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) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        try{
            BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
            int size = Integer.parseInt(read.readLine());
            for(int i=0;i<size;i++){
                int n = Integer.parseInt(read.readLine());
                int arr[][] = new int[n][2];
                for(int j=0;j<n;j++){
                    String input = read.readLine();
                    String tarr[] = input.split(" ");
                    arr[j][0] = Integer.parseInt(tarr[0]);
                    arr[j][1] = Integer.parseInt(tarr[1]);
                }
                boolean flag1 = true;
                int xmax = Integer.MIN_VALUE;
                int xmin = Integer.MAX_VALUE;
                int ymax = Integer.MIN_VALUE;
                int ymin = Integer.MAX_VALUE;
                if(n>0){
                    for (int j=0;j<n ;j++ ) {
                        if(arr[j][0]>xmax){
                            xmax = arr[j][0];
                        }
                        if (arr[j][0]<xmin) {
                            xmin = arr[j][0];
                        }
                        if (arr[j][1]>ymax) {
                            ymax = arr[j][1];
                        }
                        if(arr[j][1]<ymin){
                            ymin = arr[j][1];
                        }
                    }
                    for (int j=0;j<n;j++ ) {
                        if(arr[j][0]==xmax||arr[j][0]==xmin){
                            
                        }else if(arr[j][1]==ymax||arr[j][1]==ymin){
                            
                        }else{
                            flag1 =false;
                        }
                    }
                }
                if(flag1){
                    System.out.println("YES");
                }else{
                    System.out.println("NO");
                }
            }
        }catch(Exception e){
            System.out.println(e.toString());
        }
    }
}