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();
        for (int z = 0; z < q; z++) {
            int n = sc.nextInt();
            int[] x = new int[n];
            int[] y = new int[n];
            int minx = 1000000;
            int miny = 1000000;
            int maxx = -1000000;
            int maxy = -1000000;
            for (int i = 0; i < n; i++) {
                x[i] = sc.nextInt();
                y[i] = sc.nextInt();
                minx = Math.min(minx, x[i]);
                miny = Math.min(miny, y[i]);
                maxx = Math.max(maxx, x[i]);
                maxy = Math.max(maxy, y[i]);
            }
            String ans = "YES";
            for (int i = 0; i < n; i++) {
                if (x[i]!=minx&&x[i]!=maxx&&y[i]!=miny&&y[i]!=maxy)
                    ans = "NO";
            }
            System.out.println(ans);
        }
    }
}