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 scan = new Scanner(System.in);
        int q = scan.nextInt();
        for(int i=0;i<q;i++){
            int n = scan.nextInt();
            int[] xPoint = new int[n];
            int[] yPoint = new int[n];
            
            for(int j=0;j<n;j++){
                xPoint[j] = scan.nextInt();
                yPoint[j] = scan.nextInt();                                   
            }
            int maxforX = Integer.MIN_VALUE;
            for(int j=0;j<n;j++){
               if(xPoint[j]>maxforX){
                   maxforX = xPoint[j];
               }
            }
            int maxforY = Integer.MIN_VALUE;
            for(int j=0;j<n;j++){
               if(yPoint[j]>maxforY){
                   maxforY = yPoint[j];
               }
            }
            for(int j=0;j<n;j++){
                if(xPoint[j]<maxforX && yPoint[j]<maxforY && xPoint[j]>0 && yPoint[j]>0)
                    System.out.println("NO");
            }
            int[] flag = new int[n];
            for(int j=0;j<n;j++){
                if(xPoint[j]==0 || yPoint[j]==0){
                   flag[j]=1;
                }
                else{
                    flag[j]=0;
                }
            }
            int flagRise = 0;
            for(int j=0;j<n;j++){
                if(flag[j]==1)
                    continue;
                flagRise = 1;
            }
            if(flagRise == 0){
                System.out.println("YES");
            }
            
        }
    }
}