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 queries = sc.nextInt();
        for(int i = 0; i < queries; i++){
            int points = sc.nextInt();
            HashMap<Integer, Integer> xMap = new HashMap<Integer, Integer>();
            HashMap<Integer, Integer> yMap = new HashMap<Integer, Integer>();
            Integer frequency = null;
            for(int j = 0; j < points; j++){                       
                int temp = sc.nextInt();
                frequency = xMap.get(temp);
                if(frequency == null)
                    xMap.put(temp, 1);
                else
                    xMap.put(temp, frequency + 1);
                int tempY = sc.nextInt();
                frequency = yMap.get(tempY);
                if(frequency == null)
                    yMap.put(tempY, 1);
                else
                    yMap.put(tempY, frequency + 1);
            }
                if(xMap.keySet().size() <= 2 || yMap.keySet().size() <= 2)
                    System.out.println("YES");
                else
                    System.out.println("NO");
         }
            
            
        }
    
}