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 sc = new Scanner(System.in);
        int m = sc.nextInt();
        for (int i=0;i<m;i++){
            int n = sc.nextInt();
            int[][] points = new int[n][2];
            int minx = sc.nextInt(); points[0][0] = minx;
            int miny = sc.nextInt(); points[0][1] = miny;
            int maxx = minx, maxy = miny;
            boolean ok = true;
            
            for (int j=1;j<n;j++){
                int x = sc.nextInt();
                int y = sc.nextInt();
                points[j][0] = x;
                points[j][1] = y;
                if (x < minx) minx = x; if (y < miny) miny = y;
                if (x > maxx) maxx = x; if (y > maxy) maxy = y;
            }
            for (int j=0;j<n;j++){
                if (points[j][0] == minx || points[j][0] == maxx) continue;
                if (points[j][1] == miny || points[j][1] == maxy) continue;
                ok = false;
            }
            if (ok)
                System.out.println("YES");
            else
                System.out.println("NO");
        }
    }
}