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

public class Solution {
    public static void runProgram(Scanner in){
        int n=in.nextInt();
        int[][] coordinates= new int[n][2];
        for (int i=0;i<n;i++){
            coordinates[i][0]=in.nextInt();
            coordinates[i][1]=in.nextInt();
            int counter=i;
            while(counter>0){
                if (!(coordinates[counter][0]== coordinates[i][0] || coordinates[counter][1]== coordinates[i][1]))
                    {
                    
                }
                else{
                    System.out.println("YES");
                    return;
                }
                counter--;
            }
        }
        System.out.println("NO");
    }

    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 in=new Scanner(System.in);
        int qurry=in.nextInt();
        for (int i=0;i<qurry;i++){
            runProgram(in);
        }
        
    }
}