#include<iostream>
using namespace std;
int main()
{
	long int i,x,q,k,n,a[10000],b[10000],min=99999,max=-99999;
	cin>>q;
	for(k=0;k<q;k++)
	{
		cin>>n;min=99999;max=-99999;
		for(i=0;i<n;i++)
		{
			cin>>a[i]>>b[i];
			if(a[i]<=min)
			  min=a[i];
			if(b[i]>=max)
			  max=b[i];  
		}
		x=0;
		for(i=0;i<n;i++)
		{
			
			if(a[i]!=min && b[i]!=min && a[i]!=max && b[i]!=max)
			{
				cout<<"NO"<<endl;x=1;break;
			}
		}
		if(x==0)
		  cout<<"YES"<<endl;
	}
}