import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.HashSet;



 
 public class Solution{
    
      static InputStream is;
         private static byte[] inbuf = new byte[1024];
         static int lenbuf = 0, ptrbuf = 0;
         static String INPUT = "";


          public static void main(String args[]) throws IOException 
        {

            is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
            java.io.PrintWriter out = new java.io.PrintWriter(System.out);
          int q = ni();
          int n;
          int a[][];
          boolean counter;
          boolean flag;
          while(q-- > 0)
          {
              flag = true;
              n = ni();
              int x,y,lx = -100000,mx = 100000;
              int ly = -100000,my = 100000;
                          counter = true;
              int array[][]= new int[n][2];
              for (int i =0 ;i<n;i++)
              {
                   array[i][0] = (ni());
                   array[i][1] = (ni());
                   if (array[i][0] > lx )
                       lx = array[i][0];
                   if (array[i][1] > ly)
                       ly =  array[i][1];
                   if (array[i][0] < mx )
                       mx = array[i][0];
                   if (array[i][1] < my)
                       my =  array[i][1];
              }
             
              for (int i =0 ;i<n;i++)
              {
                   x = array[i][0];
                   y = array[i][1];
                   if ((x) != lx && (x) != (mx))
                   {
                       if((y) != (ly) && (y) != (my))
                       flag = false;
                   }
                   else
                   {
                       if ((y) > (ly) && (y) < (my))
                           flag = false;
                   }
                   
              }
             
          
          if(flag)
          {
          out.println("YES");
          }else
          {
              out.println("NO");
          }
          }
            out.close();

        }
       
     private static int ni()
            {
                    int num = 0, b;
                    boolean minus = false;
                    while((b = readByte()) != -1 && !((b >= '0' && b <= '9')|| b == '-'));
                    if(b == '-'){
                            minus = true;
                            b = readByte();
                    }
                    while(true){
                            if(b >= '0' && b <= '9'){
                                    num = num * 10 + (b - '0');
                            }else{
                                    return minus ? -num : num;
                            }
                            b = readByte();
                    }
            }
     private static long ln()
            {
                    long num = 0, b;
                    boolean minus = false;
                    while((b = readByte()) != -1 && !((b >= '0' && b <= '9')|| b == '-'));
                    if(b == '-'){
                            minus = true;
                            b = readByte();
                    }
                    while(true){
                            if(b >= '0' && b <= '9'){
                                    num = num * 10 + (b - '0');
                            }else{
                                    return minus ? -num : num;
                            }
                            b = readByte();
                    }
            }
          private static String str()
            {
                    StringBuffer num=new StringBuffer() ;
                    int b;

                    while((b = readByte()) != -1 && !((b >= '0' && b <= '9')|| b == '.'|| b == '-'||(b >= 'a' && b <= 'z')));
                            while(true){
                            if(b >= '0' && b <= '9'|| b == '.'|| b == '-'||(b >= 'a' && b <= 'z')){
                                    num=num.append((char)b);
                            }else{
                                    return num.toString();
                            }
                            b = readByte();
                    }
            }
    private static int readByte()
            {

                    if(ptrbuf >= lenbuf){
                            ptrbuf = 0;
                            try { lenbuf = is.read(inbuf); } catch (IOException e) { }
                            if(lenbuf <= 0)return -1;
                    }
                    return inbuf[ptrbuf++];
            }

    }