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);
        long q = in.nextLong();
        for(int iii = 0; iii < q; iii++){
            int n = in.nextInt();
            int x[] = new int[n];
            int y[] = new int[n];
            int xm = Integer.MAX_VALUE;
            int xx = Integer.MIN_VALUE;
            int ym = Integer.MAX_VALUE;
            int yx = Integer.MIN_VALUE;
            
            for(int i = 0; i < n; i++){
                x[i] = in.nextInt();
                y[i] = in.nextInt();
                
                xm = Math.min(xm, x[i]);
                xx = Math.max(xx, x[i]);
                ym = Math.min(ym, y[i]);
                yx = Math.max(yx, y[i]);
            }
            boolean possible = true;
            for(int i = 0; i < n; i++){
                if(x[i] != xm && x[i] != xx && y[i] != ym && y[i] != yx){
                    possible = false;
                    break;
                }
            }
            
            System.out.println(possible?"YES":"NO");
        }
    }
}