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

        for(int qi = 0; qi < q; qi++) {
            int n = scan.nextInt();
            int[] x = new int[n];
            int[] y = new int[n];
            for(int i = 0; i < n; i++) {
                x[i] = scan.nextInt();
                y[i] = scan.nextInt();
            }
            
            String answer = "YES";
            
            Integer maxX = null;
            Integer minX = null;
            Integer maxY = null;
            Integer minY = null;
            
            for(int i = 0; i < n; i++) {
                if(maxX == null) {
                    maxX = minX = x[i];
                    maxY = minY = y[i];
                }
                if(x[i] > maxX) {
                    maxX = x[i];
                } else if (x[i] < minX) {
                    minX = x[i];
                }
                if(y[i] > maxY) {
                    maxY = y[i];
                } else if (y[i] < minY) {
                    minY = y[i];
                }
            }
            for(int i = 0; i < n; i++) {
                if(x[i] != maxX && x[i] != minX && y[i] != maxY && y[i] != minY) {
                    answer = "NO";
                    break;
                }
            }
            

            System.out.println(answer);

        }

    }

}