import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
//import java.util.HashMap;
import java.util.StringTokenizer;


public class test {
    public static void main(String[] args) throws NumberFormatException, IOException{
        PrintWriter pw= new PrintWriter(System.out);
        // StringBuffer buff=new StringBuffer("");
        StringTokenizer token;
        BufferedReader in= new BufferedReader(new InputStreamReader(System.in));

        int t=Integer.parseInt(in.readLine());
        int n,minx=0, maxx=0,miny=0,maxy=0;
        int[] arra;
        int[] arrb;
        boolean bool=true;
        for (int i = 0; i < t; i++) {
            n=Integer.parseInt(in.readLine());
            arra=new int[n];
            arrb=new int[n];
            for (int j = 0; j < n; j++) {
                token=new StringTokenizer(in.readLine());

                arra[j]=Integer.parseInt(token.nextToken());
                arrb[j]=Integer.parseInt(token.nextToken());
                if(arra[j]<minx)
                    minx=arra[j];
                if(arrb[j]<miny)
                    miny=arrb[j];
                if(arra[j]>maxx)
                    maxx=arra[j];
                if(arrb[j]>maxy)
                    maxy=arrb[j];
            }
            for (int j = 0; j < n; j++) {
                if(((arra[j]<maxx) && (arra[j]>minx)) && ((arrb[j]<maxy) && (arrb[j]>miny))){
                    bool=false;
                    break;
                }
            }
            if(bool==true)
                pw.println("YES");

            else
                pw.println("NO");

        }

        pw.flush();
        pw.close();
    }
}