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

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 in = new Scanner(System.in);
        int q = in.nextInt();
        for(int k = 0; k < q; k++){
            int n = in.nextInt();
            int[] x = new int[n];
            int[] y = new int[n];
            int minx = 100000;
            int maxx = -100000;
            int miny = 100000;
            int maxy = -100000;
            for(int i = 0; i < n; i++){
                x[i] = in.nextInt();
                y[i] = in.nextInt();
                if(x[i] < minx)minx=x[i];
                if(x[i] > maxx)maxx=x[i];
                if(y[i] < miny)miny=y[i];
                if(y[i] > maxy)maxy=y[i];
            }
            int cond = 0;
            for(int i = 0; i < n; i++){
                //if((x[i] != minx && x[i] != maxx) || (y[i] != miny && y[i] != maxy))cond = 1;
                //if(y[i] != miny && y[i] != maxy)cond=1;
                if(x[i] == minx || x[i] == maxx){
                    if(y[i] < miny || y[i] > maxy)cond=1;
                }else if(y[i] == miny || y[i] == maxy){
                    if(x[i] < minx || x[i] > maxx)cond=1;
                }else{
                    cond=1;
                }
            }
            if(cond != 0){
                System.out.println("NO");
            
            }else{
                System.out.println("YES");
            }
            
        }
    }
}