#include<bits/stdc++.h>
using namespace std;
int main()
{
	int T;
	cin>>T;
	while(T--)
	{
		int N;
		cin>>N;
		int i;
		vector<pair<int,int> >V1,V2;
		
		for (i=0;i<N;i++)
		{
			int x,y;
			cin>>x>>y;
			V1.push_back(make_pair(x,y));
			V2.push_back(make_pair(y,x));
		}
		
		sort(V1.begin(),V1.end());
		sort(V2.begin(),V2.end());
		
		int flag=1,taken[15]={0};
		
		int x1=V1[0].first,x2=V1[N-1].first;
		int y1=V2[0].first,y2=V2[N-1].first;
		
		for (i=0;i<N;i++)
		{
			int p=V1[i].first;
			int q=V1[i].second;
			
			if(p==x1 || p==x2 || q==y1 || q==y2)
			continue;
			
			else
			{
				flag=0;break;
			}
		}
		
		if(flag)
		{
			printf("YES\n");
		}
		
		else printf("NO\n");
	}
	
}