#include<bits/stdc++.h>
using namespace std;
int main()
{
	long long q;
	vector<pair<long long ,long long> > v;
	cin>>q;
	while(q--)
	{
		
		v.clear();
		long long n,x,y,m1=-1,m2=-1,m3=0,m4=0;
		cin>>n;
		int flag=0;
		for(long long i=0;i<n;i++)
		{
			cin>>x>>y;
			v.push_back(make_pair(x,y));
			
				
				m1=max(x,m1);
				m2=max(y,m2);
				if(i==0)
				{
					m3=x;
					m4=y;
					}	
					else
					{
						m3=min(m3,x);
						m4=min(m4,y);
					}
			/*	else
				{
					if(x<m1 && y!=m2 )
					{
						flag=1;
						break;
					}
					else if( x>m1)
					{
						flag=1;
						break;
					}
					if(y<m2 && x!=m1 )
					{
						flag=1;
						break;
					}
					else if( y>m2)
					{
						flag=1;
						break;
					}
					
			   }		
			}
			else if(x==0)
			{
				if(m2==-1)
				m2=y;
				else
				{
					m2=max(m2,y);
				}
			}*/
		}
		for(long long i=0;i<n;i++)
		{
			if((v[i].first==m1 || v[i].first==m3 ) &&(v[i].second==m2 || v[i].second==m4 ) )
			continue;
			
			 else if((v[i].first<m1 && v[i].first>m3 )) 
					{
						if(v[i].second!=m2 && v[i].second!=m4)
						{
							flag=1;
							break;
						}
						
					}
				else	if((v[i].first<m1 && v[i].first>m3 )) 
					{
						if(v[i].first!=m1 && v[i].first!=m3)
						{
						 flag=1;
						break;}
					}
				}
		if(flag==0)
		cout<<"YES"<<endl;
		else
		cout<<"NO"<<endl;
	}
	return 0;
}