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) {
        Scanner in = new Scanner(System.in);
        int testCases = Integer.parseInt(in.nextLine());
        while(testCases > 0){
            int dots = in.nextInt();
            
            Map<Integer, Integer> x = new HashMap<>();
            Map<Integer, Integer> y = new HashMap<>();
            for (int i = 0; i < dots; i++) {
                int nextX = in.nextInt();
                int nextY = in.nextInt();
                if (!x.containsKey(nextX)) {
                    if (!y.containsKey(nextY)) {
                       // System.out.println("putting x = " + nextX + " in");
                        x.put(nextX, 0);
                        //System.out.println("putting y = " + nextY + " in");
                        y.put(nextY, 0);
                    } 
                    
                }
                if (!y.containsKey(nextY)) {
                    if (!x.containsKey(nextX)) {
                        //System.out.println("putting x = " + nextX + " in");
                        x.put(nextX, 0);
                        //System.out.println("putting y = " + nextY + " in");
                        y.put(nextY, 0);
                    } 
                    
                }
                
            }
            
            if (x.size() <= 2 && y.size() <= 2) {
                System.out.println("YES");
            } else {
                System.out.println("NO");
            }
            
            testCases--;
      }
    }
}