#include <bits/stdc++.h>
#define ll long long

using namespace std;
pair <int,int> p1[15],p2[15];
int main()
{
    //freopen("i.txt","r",stdin);
	int n;
	cin>>n;
	int p;
	for(int i=0;i<n;i++)
	{
		cin>>p;
		int x,y;
		for(int j=0;j<p;j++)
		{
			cin>>x>>y;
			p1[j] = make_pair(x,y);
			p2[j] = make_pair(y,x);
		}
		sort(p1,p1+p);
		sort(p2,p2+p);
		int mix = p1[0].first, maX = p1[p-1].first;
		int miy = p1[0].first, may = p1[p-1].first;
		bool f=true;
		for(int j=0;j<p;j++)
		{
			if(p1[j].first == mix or p2[j].first == maX)
			{
				if(p1[j].second>=miy and p1[j].second <= may)
				{

				}
				else
				{
					f=false;
				}		
			}
			else if (p1[j].second == miy or p2[j].second == may)
			{
				if(p1[j].first>=mix and p1[j].first <= maX)
				{

				}
				else
				{
					f=false;
				}		
			}
			else
				f=false;
		}
		if(f)
			cout<<"YES"<<endl;
		else
			cout<<"NO"<<endl;
	}

	return 0;
}