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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    int q;
    cin>>q;
    for(int z=0;z<q;z++)
   {
        int n;
        cin>>n;
        vector<int> x1;
        vector<int> y1;
        set<int> x;
        set<int> y;
        for(int i=0;i<n;i++)
        {
        	int a,b;
        	cin>>a>>b;
        	x.insert(a);
        	y.insert(b);
        	x1.push_back(a);y1.push_back(b);
		}
		int minx,maxx,miny,maxy;
		set<int>::iterator it;
		it=x.begin();
		minx=*it;
		it=x.end();
        --it;
		maxx=*it;
		it=y.begin();
		miny=*it;
		it=y.end();
        --it;
		maxy=*it;
		
        //cout<<minx<<maxx<<miny<<maxy<<endl<<endl;
		/*for(int i=0;i<n;i++)
            {
            cout<<x1[i]<<y1[i]<<endl;
        }*/
        
        int flag=1;
		for(int i=0;i<n;i++)
		{
			if((x1[i]!=maxx)&&(x1[i]!=minx)&&(y1[i]!=miny)&&(y1[i]!=maxy))
			{
				flag=0;
				break;
			}
		}
		if(flag)
        {cout<<"YES\n";}
		else
        {cout<<"NO\n";}
    }
    return 0;
}