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


int main() {
    long long T,N,i;
    cin>>T;
   while(T--)
        {
     cin>>N;
     //   v.clear();
        vector<pair<int,int>>v;
        for(i=0;i<N;i++)
            {
            int x,y;
            cin>>x>>y;
            v.push_back(make_pair(x,y));
        }
        sort(v.begin(),v.end());
        int A,B,C,D;
        A=v[0].first;B=v[0].second;
        C=v[N-1].first;D=v[N-1].second;
        int flag=1;
         for(i=0;i<N;i++)
             {
             if(v[i].first==A && (v[i].second>=B || v[i].second<=D))
             {flag=1;
             }
             else if(v[i].second==D &&(v[i].first>=A || v[i].first<=C))
                 flag=1;
             else if(v[i].first==C && (v[i].second>=B || v[i].second<=D))
                  flag=1;
             else if(v[i].second==B &&(v[i].first>=A || v[i].first<=C))
                 flag=1;
                 else
             {flag=0;
             break;}
         }
        if(flag)
            cout<<"YES\n";
        else 
            cout<<"NO\n";
    }
 
    
    return 0;
}