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

int main() {
        int q;
        cin>>q;
        for(int a0=0;a0<q;a0++)
        {
        	int n;
        	cin>>n;
        	int a[n],b[n],maxa=-10000,maxb=-10000,mina=10000,minb=10000;
        	bool flag=false;
        	for(int i=0;i<n;i++)
        	{
        		cin>>a[i]>>b[i];
        	//	cout<<a[i]<<b[i];
        		if(a[i]>maxa)
        		{
        			maxa=a[i];
        	//		cout<<mina;
				}
				if(b[i]>maxb)
				{
					maxb=b[i];
				}
				if(a[i]<mina)
        		{
        			mina=a[i];
				}
				if(b[i]<minb)
				{
					minb=b[i];
				}
			}
		/*	for(int i=0;i<n;i++)
			{
				cout<<a[i]<<" "<<b[i];
			}*/
		//	cout<<mina<<minb<<maxa<<maxb;
		/*	if(n<=2)
        	{
        	cout<<"YES"<<endl;
        	}
			else
        	{*/
        		for(int i=0;i<n;i++)
        		{
        			if(a[i]!=mina&&a[i]!=maxa&&b[i]!=minb&&b[i]!=maxb)
        			{
        				flag=true;
        				break;
					}
					
				}
				if(flag==true)
				{
					cout<<"NO"<<endl;
				}
				else
				{
					cout<<"YES"<<endl;
				}
			}
		//}

      
    return 0;
}