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 sc = new Scanner(System.in);
        int t = sc.nextInt();
        outer: while (t--!=0){

            int n = sc.nextInt();
            int [] x = new int[n];
            int [] y = new int[n];

            for(int i=0;i<n;i++){
                x[i] = sc.nextInt();
                y[i] = sc.nextInt();
            }
            int minX =Integer.MAX_VALUE,maxX=Integer.MIN_VALUE;
            for(int i=0;i<n;i++){
                minX = Math.min(minX,x[i]);
                maxX = Math.max(maxX,x[i]);
            }
            int minY =Integer.MAX_VALUE,maxY=Integer.MIN_VALUE;
            for(int i=0;i<n;i++){
                minY = Math.min(minY,y[i]);
                maxY = Math.max(maxY,y[i]);
            }

            for(int i=0;i<n;i++){
                if(x[i]==minX || x[i]==maxX) continue;
                if(y[i]==minY || y[i] ==maxY) continue;
                System.out.println("NO");
                continue outer;
            }
            System.out.println("YES");




        }
    }
}