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

public class Solution {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int numQueries = scanner.nextInt();
        for(int thisQuery = 0; thisQuery < numQueries; thisQuery++){
            int numPoints = scanner.nextInt();
            int[] X = new int[numPoints];
            int[] Y = new int[numPoints];
            for(int thisPoint = 0; thisPoint < numPoints; thisPoint++){
                X[thisPoint] = scanner.nextInt();
                Y[thisPoint] = scanner.nextInt();
            }
            Set<Integer> setx = new HashSet<Integer>();
            Set<Integer> sety = new HashSet<Integer>();
            for(int i = 0; i < X.length; i++){
                setx.add(X[i]);
                sety.add(Y[i]);
            }
            if(setx.size() > 2 || sety.size() > 2){
                System.out.println("NO");
            }
            else{
                System.out.println("YES");
            }
        }
    }
}