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 in = new Scanner(System.in);
        int q = in.nextInt();
        while(q-->0) {
            int n = in.nextInt();
            int xMax = Integer.MIN_VALUE;
            int xMin = Integer.MAX_VALUE;
            int yMax = Integer.MIN_VALUE;
            int yMin = Integer.MAX_VALUE;
            List<Pos> p = new LinkedList();
            
            for (int i = 0; i < n; i++) {
                int x = in.nextInt();
                int y = in.nextInt();
                
                if (x > xMax)
                    xMax = x;
                if (x < xMin)
                    xMin = x;
                if (y > yMax)
                    yMax = y;
                if (y < yMin)
                    yMin = y;
                
                p.add(new Pos(x,y));
            }
            boolean ans = true;
            for (Pos c : p) {
                if (c.x != xMax && c.x != xMin && c.y != yMax && c.y != yMin) {
                    ans = false;
                    break;
                }
            }
            
            System.out.println(ans ? "YES" : "NO");
        }
    }
    
}

class Pos {
    int x;
    int y;
    public Pos(int x, int y) {
        this.x = x;
        this.y = y;
    }
}