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) {
        
        try(Scanner scan = new Scanner(System.in)) {
            int q = scan.nextInt();
            
            while(q-- > 0) {
                
                int n = scan.nextInt();
                
                int minx = Integer.MAX_VALUE;
                int maxx = Integer.MIN_VALUE;
                int miny = Integer.MAX_VALUE;
                int maxy = Integer.MIN_VALUE;
                int xMiny = Integer.MAX_VALUE;
                int xMaxy = Integer.MIN_VALUE;
                int yMinx = Integer.MAX_VALUE;
                int yMaxx = Integer.MIN_VALUE;
                
                int[][] points = new int[n][2];
                while(n-- > 0) {
                    
                    int x = scan.nextInt();
                    int y = scan.nextInt();
                    
                    points[n][0] = x;
                    points[n][1] = y;
                    
                    if(x < minx)
                        minx = x;
                    if(x > maxx)
                        maxx = x;
                    
                    if(y < miny)
                        miny = y;
                    if(y > maxy)
                        maxy = y;
                }
                
                int len = points.length;
                boolean result = true;
                while(len-- > 0) {
                    
                    if((points[len][0] <= maxx && points[len][0] >= minx && (points[len][1] == miny || points[len][1] == maxy)) || 
                       (points[len][0] == maxx || points[len][0] == minx && (points[len][1] >= miny || points[len][1] <= maxy))) {
                        
                    }
                    else {
                        result = false;
                        break;
                    }
                }   
                
                if(result)
                    System.out.println("YES");
                else
                    System.out.println("NO");
            }
        }
    }
}