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 count = 0; count < q; count++)
        {
        	int n = in.nextInt();
        	ArrayList<Integer> xList = new ArrayList<Integer>();
        	ArrayList<Integer> yList = new ArrayList<Integer>();
        	for (int num = 0; num < n; num++)
        	{
        		int x = in.nextInt();
        		int y = in.nextInt();
        		xList.add(x);
        		yList.add(y);
        	}
        	
        	if (n <= 2 || 
        		(xList.size() == 2 && yList.size() == 2))
    		{
        		System.out.println("YES");
    		}
        	else
        	{
        		System.out.println("NO");
        	}
        }
        
        in.close();
    }
}