#include<bits/stdc++.h>
using namespace std;

int main()
{
	
	int q;
	
	scanf("%d",&q);
	
	while(q--)
	{
		
		int n;
		
		scanf("%d",&n);
		
		pair<long long int,long long int> s[n];
		
		long long int miny = 10000000000000000,minx=10000000000000000,maxx=-110000000000000,maxy=-100000000000000000;
		
		for(int i = 0;i < n;i++)
		{
			
			scanf("%lld %lld",&s[i].first,&s[i].second);
			miny = min(miny,s[i].second);
			minx = min(minx,s[i].first);
			maxx = max(maxx,s[i].first);
			maxy = max(maxy,s[i].second);
		
		}
		
		bool flag = true;
		
		for(int i = 0;i < n;i++)
		{
			
			if((s[i].first == minx || s[i].first == maxx) && (s[i].second >= miny && s[i].second <= maxy))
			{
				
				flag = true;
				
			}
			else if((s[i].second == miny || s[i].second == maxy) && (s[i].first >= minx && s[i].first <= maxx))
			{
				
				;
				
			}
			else
			{
				flag = false;
				break;
			}
		}
		
		if(flag)
		  printf("YES\n");
		else
		  printf("NO\n");
		  
		  
	}
	
	return 0;
	
}