import java.io.*;
import java.util.*;
import java.math.*;

public class Solution {
    
    static class Point {
        int x;
        int y;
        
        public Point(int x, int y) {
            this.x = x;
            this.y = y;
        }
    }
    
    public static boolean check(List<Point> list) {
        int minX = Integer.MAX_VALUE;
        int maxX = Integer.MIN_VALUE;
        int minY = Integer.MAX_VALUE;
        int maxY = Integer.MIN_VALUE;
        for (Point p : list) {
            if (p.x > maxX) {
                maxX = p.x;
            }
            if (p.x < minX) {
                minX = p.x;
            }
            if (p.y > maxY) {
                maxY = p.y;
            }
            if (p.y < minY) {
                minY = p.y;
            }
        }
        for (Point p : list) {
            if ((p.x >= minX && p.x <= maxX && p.y == maxY) ||
                (p.x >= minX && p.x <= maxX && p.y == minY) ||
                (p.y >= minY && p.y <= maxY && p.x == maxX) ||
                (p.y >= minY && p.y <= maxY && p.x == minX)) {
            } else {
                return false;
            }
        }
        return true;
    }

    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 t = in.nextInt();
        while (t > 0) {
            int n = in.nextInt();
            List<Point> list = new ArrayList<>();
            for (int i=0; i<n; i++) {
                int x = in.nextInt();
                int y = in.nextInt();
                Point p = new Point(x,y);
                list.add(p);
            }
            if (n < 3) {
                System.out.println("YES");
            } else {
                boolean is = check(list);
                System.out.println(is ? "YES" : "NO");
            }
            t--;
        }
    }
}