#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <set>
using namespace std;
long long n,q;
long long a,b;
vector <long long> xes,yes,nxes,nyes;
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */  
    cin>>q;
    while(q--)
        {
        yes.clear();
        xes.clear();
        nyes.clear();
        nxes.clear();
        cin>>n;
        if(n==1)
            {
            cout<<"YES"<<endl;
        }
       
        else
            {
            while(n--)
                {
            cin>>a>>b;
            xes.push_back(a);
                nxes.push_back(a);
            yes.push_back(b);
                nyes.push_back(b);
                
                
        }
            sort(xes.begin(),xes.end());
                sort(yes.begin(),yes.end());
                long long xmax=xes[xes.size()-1];
                long long xmin=xes[0];
                long long ymax=yes[yes.size()-1];
                long long ymin=yes[0];
                long long i=0;
                if(xmax==xmin || ymax==ymin)
                    cout<<"NO"<<endl;
            else{
                bool found=true;
                while(i<nxes.size()&&(found))
                    {
                    if((nxes[i]==xmax || nxes[i]==xmin)||(nyes[i]==ymax || nyes[i]==ymin))
                        {
                        i++;
                    }
                    else
                        {
                        found=false;
                    }
                    
                }
                
                if(found)
                    {
                    cout<<"YES"<<endl;
                }
                else
                    {
                    cout<<"NO"<<endl;
                }
            }
        }
    }
    return 0;
}