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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int t;
    cin>>t;
    for(int i=0;i<t;i++){
        int n;
        cin>>n;
        vector<pair<int,int>>v;
        int xmin=INT_MAX,xmax=INT_MIN,ymin=INT_MAX,ymax=INT_MIN;
        for(int j=0;j<n;j++){
            int x,y;
            cin>>x>>y;
            pair<int,int>p;
            p.first=x;
            p.second=y;
            v.push_back(p);
            if(x>xmax){
                xmax=x;
            }
            if(x<xmin){
                xmin=x;
            }
             if(y>ymax){
                ymax=y;
            }
            if(y<ymin){
                ymin=y;
            }
            
        }
        int possible=1;
        for(int j=0;j<n;j++){
            pair<int,int>p=v[j];
            
                int x=p.first;
                int y=p.second;
                if((x==xmin&&y==ymin)||(x==xmin&&y==ymax)||(x==xmax&&y==ymin)||(x==xmax&&y==ymax)){
                    
                }
                 else{
                    if(x==xmin){
                        if(!(y>=ymin&&y<=ymax)){
                            possible=0;
                            break;
                        }
                    }
                     else if(x==xmax){
                          if(!(y>=ymin&&y<=ymax)){
                            possible=0;
                            break;
                        }
                     }
                     else if(y==ymin){
                         if(!(x>=xmin&&x<=xmax)){
                            possible=0;
                            break;
                        }
                     }
                     else if(y==ymax){
                         if(!(x>=xmin&&x<=xmax)){
                            possible=0;
                            break;
                        }
                     }
                     else{
                         possible=0;
                         break;
                     }
                    }
        }
        if(possible==1)cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
        
    }
    return 0;
}