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



int main() {

    int i,j,k,n,q,x,y;
   
    
    cin>>q;
    
    while(q--)
        {
        
     vector< pair<int,int> > pts;      
        cin>>n;
        
        cin>>x>>y;
        
        int xmin=x,xmax=x,ymin=y,ymax=y;
        
        pts.push_back(pair<int,int>(x,y));
        for(i=1;i<n;i++)
            {
            
            cin>>x>>y;
            pts.push_back(pair<int,int>(x,y));
            
            if(x<xmin)
                xmin=x;
            if(x>xmax)
                xmax=x;
            
             if(y<ymin)
                ymin=y;
            if(y>ymax)
                ymax=y;
            
            }
        
        int flag=1;
        
                    
        
        
        for(i=0;i<pts.size();i++)
            {
            
                x=pts[i].first;
                y=pts[i].second;
            
       if(!((y==ymin&&(x<=xmax&&x>=xmin))||(y==ymax&&(x<=xmax&&x>=xmin))||(x==xmin&&(y<=ymax&&y>=ymin))||(x==xmax&&(y<=ymax&&y>=xmin))))
       {flag=0;break;}
                
            
        }
        
        
        if(flag)
            cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
        
        
    }
    
    return 0;
}