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 test = 0 ; test < q ; test++) {
            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 x[] = new int[n];
            int y[] = new int[n];
            for(int i = 0 ; i < n ; i++) {
                x[i] = in.nextInt();
                y[i] = in.nextInt();
                maxX = Math.max(maxX, x[i]);
                maxY = Math.max(maxY, y[i]);
                minX = Math.min(minX, x[i]);
                minY = Math.min(minY, y[i]);
            }
            boolean possible = true;
            for(int i = 0 ; i < n ; i++) {
            	if((x[i] == minX ) ||
            			(x[i] == maxX ) ||
            			(y[i] == minY) ||
            			(y[i] == maxY)) {
            		possible = true;
            	} else {
            		possible = false;
            		break;
            	}
            }
            if(!possible) {
            	System.out.println("NO");
            } else {
            	System.out.println("YES");
            }
        }
    }
}