#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int main()
{
	int n=0,m=0,sum=0,q=0,x,y,nn=0,i=0,flag=0,max_x=-99999999,max_y=-99999999,min_x=99999999,min_y=99999999,ary[11][11]={0};
	
	scanf("%d",&q);
	while(q--)
	{
		scanf("%d",&n);
		nn=n;
		i=0;
		while(n--)
		{
			scanf("%d %d",&x,&y);
			ary[i][0]=x;
			ary[i][1]=y;
			
			if(max_x<=x)
				max_x=x;
			if(max_y<=y)
				max_y=y;
			if(min_x>=x)
				min_x=x;
			if(min_y>=y)
				min_y=y;
			i++;
		}
		i=0;
		flag=0;
		while(nn--)
		{
			if(ary[i][0]<max_x && ary[i][0]>min_x)
			{
				if(ary[i][1]==max_y)
				{
					
				}
				else if(ary[i][1]==min_y)
				{
					
				}
				else
				{
					flag=1;
				}
			}
			else if(ary[i][0]==max_x)
			{
				if(ary[i][1]<=max_y && ary[i][1]>=min_y)
				{
					
				}
				else
				{
					flag=1;
				}
			}
			else if(ary[i][0]==min_x)
			{
				if(ary[i][1]<=max_y && ary[i][1]>=min_y)
				{
					
				}
				else
				{
					flag=1;
				}
			}
			else
			{
				flag=1;
			}
			i++;
		}
		if(flag==1)
		{
			printf("NO\n");
		}
		else if(flag==0)
		{
			printf("YES\n");
		}
		
	}
	return 0;
}