import java.util.*;
import java.io.*;
class FastReader
{
BufferedReader br;
StringTokenizer st;

public FastReader()
{
	br = new BufferedReader(new
			 InputStreamReader(System.in));
}

String next()
{
	while (st == null || !st.hasMoreElements())
	{
		try
		{
			st = new StringTokenizer(br.readLine());
		}
		catch (IOException  e)
		{
			e.printStackTrace();
		}
	}
	return st.nextToken();
}

int nextInt()
{
	return Integer.parseInt(next());
}

long nextLong()
{
	return Long.parseLong(next());
}

double nextDouble()
{
	return Double.parseDouble(next());
}

String nextLine()
{
	String str = "";
	try
	{
		str = br.readLine();
	}
	catch (IOException e)
	{
		e.printStackTrace();
	}
	return str;
}
}
class Solution 
{
	FastReader sc;
	int q;
	public Solution()
	{
		sc=new FastReader();
		q=sc.nextInt();
		for(int z=0;z<q;z++)
		{
			int n=sc.nextInt();
			int matrix[][]=new int[n][2];
			int minx=Integer.MAX_VALUE,miny=Integer.MAX_VALUE,maxx=Integer.MIN_VALUE,maxy=Integer.MIN_VALUE;
			for(int i=0;i<n;i++)
			{
				matrix[i][0]=sc.nextInt();
				if(matrix[i][0]<minx)
				{
					minx=matrix[i][0];
				}
				if(matrix[i][0]>maxx)
				{
					maxx=matrix[i][0];
				}
				matrix[i][1]=sc.nextInt();
				if(matrix[i][1]<miny)
				{
					miny=matrix[i][1];
				}
				if(matrix[i][1]>maxy)
				{
					maxy=matrix[i][1];
				}
			}
			//System.out.println(minx+" "+maxx+" "+miny+" "+maxy);
			int flag=0;
			for(int i=0;i<n;i++)
			{
				int x=matrix[i][0];
				int y=matrix[i][1];
				if(x!=minx && x!=maxx && y!=miny && y!=maxy)
				{
					flag=1;
					break;
				}
			}
			if(flag==1)
			{
				System.out.println("NO");
			}
			else if(flag==0)
			{
				System.out.println("YES");
			}
		}
	}
	public static void main(String[] args) 
	{
		new Solution();
	}
}