import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
		int q = in.nextInt();
		
		for (int i = 0; i < q; i++) {
			int n = in.nextInt();
			int points [][] = new int[n][2];
			
			int x0 = in.nextInt();
			int y0 = in.nextInt();
			points[0][0] = x0;
			points[0][1] = y0;
			
			int top = y0;
			int bottom = y0;
			int left = x0;
			int right = x0;
			boolean onRect = true;
			
			for (int j = 1; j < n; j++) {
				int x = in.nextInt();
				int y = in.nextInt();
				points[j][0] = x;
				points[j][1] = y;
				
				boolean thisPointOk = false;
				
				if (x <= left) {
					thisPointOk = true;
					left = x;
				} else if (x >= right) {
					thisPointOk = true;
					right = x;
				} 
				
				if (y <= bottom) {
					thisPointOk = true;
					bottom = y;
				} else if (y >= top) {
					thisPointOk = true;
					top = y;
				}
				
				if (!thisPointOk){
					onRect = false;
				}
			}
			
			if (onRect) {
			
				for (int j = 0; j < n; j++) {
					int x = points[j][0];
					int y = points[j][1];
					if ((x != left && x != right) && (y != bottom && y!= top)) {
						onRect = false;
						break;
					}
				}
			}
			
			if (onRect)
				System.out.println("YES");
			else
				System.out.println("NO");
		}
    }
}