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

public class Solution {

    public static void main(String[] args) {
        Scanner in =new Scanner(System.in);
        int q=in.nextInt();
        for(int i=0;i<q;i++){
            int n=in.nextInt();
            int ctr=0;
            int[] x=new int[n];
            
            for(int j=0;j<n;j++){
                int a=in.nextInt();
                int b=in.nextInt();
                x[j]=a;
                
            }
            int m=0;
            for(int k=1;k<n;k++){
                    if(x[k]!=x[0]){
                        m=k;
                        break;
                       
                    }
                
                }
            if(m!=0){
                for(int l=m;l<n;l++) {
                    if(x[l]!=x[m]&&x[l]!=x[0])      ctr++;
                }
            }else{
                System.out.println("YES");
            }
            if(m!=0&&ctr==0)      System.out.println("YES");
            else if(m!=0&&ctr!=0)   System.out.println("NO");
            
            }
    }
}