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 q_=0; q_<q;q_++){
            
            int n = in.nextInt();
            int maxX = Integer.MIN_VALUE;
            int minX = Integer.MAX_VALUE;
            int maxY = Integer.MIN_VALUE;
            int minY = Integer.MAX_VALUE;
            int[][] xy = new int[n][2];
            boolean ok = true;
            
            for(int n_=0; n_<n; n_++){
                int x = in.nextInt();
                int y = in.nextInt();
                if(x<minX){
                    minX = x;
                }
                if(x>maxX){
                    maxX = x;
                }
                if(y<minY){
                    minY = y;
                }
                if(y>maxY){
                    maxY = y;
                }
                xy[n_][0] = x;
                xy[n_][1] = y;
            }
            for(int i=0; i<n; i++){
                if(xy[i][0] == maxX || xy[i][1] == maxY || xy[i][0] == minX || xy[i][1] == minY){
                    continue;
                }
                else{
                    ok = false;
                    break;
                }
            }
            
            if(ok){
                System.out.println("YES");
            }
            else{
                System.out.println("NO");
            }
        }
    }
}