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


int main() {
   int q;
        cin>>q;
        while(q--)
                {
                int n;
                cin>>n;
                vector<int> a(n);
                vector<int> b(n);
                for(int i=0;i<n;i++)
                        {
                        cin>>a[i];
                        cin>>b[i];
                }
                int  x1=10001;
                int  x2=-10001;
                for(int i=0;i<n;i++)
                        {
                        if(a[i]<x1)
                                {
                                x1=a[i];
                                
                        }
                        if(a[i]>x2)
                                {
                                x2=a[i];
                        }
                }
                 int  y1=10001;
                int  y2=-10001;
                for(int i=0;i<n;i++)
                        {
                        if(b[i]<y1)
                                {
                                y1=b[i];
                                
                        }
                        if(b[i]>y2)
                                {
                                y2=b[i];
                        }
                }
                int flag=1;
                
                for(int i=0;i<n;i++)
                        {
                        if(a[i]!=x1&&a[i]!=x2&&b[i]!=y1&&b[i]!=y2)
                        {cout<<"NO"<<"\n";
                         flag=0;
                        break;
                        }
                                
                }
                if(flag==1)
                        cout<<"YES"<<"\n";
                
                
                
        }
    return 0;
}