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 sc = new Scanner(System.in);

		int q = sc.nextInt();

		while (q-- > 0) {

			int n = sc.nextInt();

			Point[] points = new Point[n];

			for (int i = 0; i < n; i++) {

				Point p = new Point(sc.nextInt(), sc.nextInt());
				
				points[i] = p;

			}
			
			Arrays.sort(points);
			
			String r = "NO";
			
			if(points.length == 1 || points.length == 2) {
				r = "YES";
			} else if(points.length == 3) {
				if(points[0].x == points[1].x && points[1].y == points[2].y)
					r = "YES";
			} else {
				if(points[0].x == points[1].x && 
						points[1].y == points[2].y &&
						points[2].x == points[3].x &&
						points[1].y == points[2].y)
					r = "YES";
			}

			System.out.println(r);
        }
        
    }
}

class Point implements Comparable<Point> {

	int x, y;

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

	@Override
	public String toString() {
		return "Point [x=" + x + ", y=" + y + "]";
	}

	@Override
	public int compareTo(Point p) {
		return x > p.x ? 1 : -1;
	}

}