#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
int compare1(pair<int,int>p1,pair<int,int>p2)
    {
      return p1.first<p2.first;
    }
int compare2(pair<int,int>p1,pair<int,int>p2)
    {
      return p1.second<p2.second;
    }

int main() {
    int t;
    cin>>t; vector<pair<int,int> >v1,v2;
    while(t--)
     {
        int n;
        cin>>n;int r,c;v1.clear();v2.clear();
        while(n--)
        {
            cin>>r>>c;
            v1.push_back(make_pair(r,c));
            v2.push_back(make_pair(r,c));
        }    
         sort(v1.begin(),v1.end(),compare1);
         sort(v2.begin(),v2.end(),compare2);
         int lc=v1[0].first;
         int rc=v1[v1.size()-1].first;
         int  dr=v2[0].second;
         int ur=v2[v2.size()-1].second;int flag=0;
        for(int i=0;i<v1.size();i++)
            {
               if(v1[i].first!=lc && v1[i].first!=rc)
                   {
                      if(v1[i].second!=dr  && v1[i].second!=ur)
                          {
                          flag=1;
                          break;}
                   }
            
            }
        if(flag==1)
            cout<<"NO"<<endl;
        else
            cout<<"YES"<<endl;
        
    }   
    return 0;
}