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);
        long q = sc.nextLong();
        for(int i=0;i<q;i++) {
        	int n = sc.nextInt();
        	Integer[][] points = new Integer[n][2];
        	Integer minX = null;
        	Integer minY = null;
        	Integer maxX = null;
        	Integer maxY = null;
        	for(int j=0;j<n;j++) {
        		points[j][0] = sc.nextInt();
        		if(minX == null || minX > points[j][0]){
        			minX = points[j][0];
        		}
        		if(maxX == null || maxX < points[j][0]){
        			maxX = points[j][0];
        		}
        		points[j][1] = sc.nextInt();
        		if(minY == null || minY > points[j][1]){
        			minY = points[j][1];
        		}
        		if(maxY == null || maxY < points[j][1]){
        			maxY = points[j][1];
        		}
        	} 
        	
        	if(n==2){
        		System.out.println("YES");
        		continue;
        	}
        	for(int j=0;j<n;j++) {
        		if(!(points[j][0] == minX || points[j][0] ==maxX || points[j][1] == minY || points[j][1] == maxY)){
        			System.out.println("NO");
        			break;
        		}
        		if(j==n-1){
        			System.out.println("YES");
        		}
        	}
        	
        }
    }
}