import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int q = in.nextInt();
        for(int i=0;i<q;i++){
            int n = in.nextInt();
            
            Double ix, ax, iy, ay;
            ix = iy = Double.POSITIVE_INFINITY;
            ax = ay = Double.NEGATIVE_INFINITY;
            
            int[] x = new int[n], y = new int[n];
            for(int j=0;j<n;j++){
                x[j] = in.nextInt();
                y[j] = in.nextInt();
                
                ix = Math.min(ix, x[j]);
                iy = Math.min(iy, y[j]);
                ax = Math.max(ax, x[j]);
                ay = Math.max(ay, y[j]);
            }
            
            String res = "YES";
            if(ix==ax && iy==ay) res = "NO";
            for(int j=0;j<n;j++){
                if(!(((x[j]==ix || x[j]==ax) && (y[j]>=iy && y[j]<=ay))
                  ||((y[j]==iy || y[j]==ay) && (x[j]>=ix && x[j]<=ax)))) 
                    res = "NO";
            }
            System.out.println(res);
        }
    }
}