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) {
        /* 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();
		for (int k = 0; k < q; k++) {
			int n = in.nextInt();
			int[] x = new int[n];
			int[] y = new int[n];
			for (int i = 0; i < n; i++) {
				x[i] = in.nextInt();
				y[i] = in.nextInt();
			}
			int ixmin = 0;
			int iymin = 0;
			int ixmax = 0;
			int iymax = 0;
			for (int i = 0; i < n; i++) {
				if (x[ixmin] > x[i]) ixmin = i;
				if (y[iymin] > y[i]) iymin = i;
				if (x[ixmax] < x[i]) ixmax = i;
				if (y[iymax] < y[i]) iymax = i;
			}
			int xmin = x[ixmin];
			int ymin = y[iymin];
			int xmax = x[ixmax];
			int ymax = y[iymax];
			boolean flag = true;
			for (int i = 0; i < n; i++) {
				if (x[i] != xmin && x[i] != xmax && y[i] != ymin && y[i] != ymax) {
					flag = false;
					break;
				}
			}
			if (flag) {
				System.out.println("YES");
			} else {
				System.out.println("NO");
			}
        }
    }
}