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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int q;
    cin>>q;
    while(q--)
        {
        int n,i;
        cin>>n;
        pair<int,int> p;
        vector<pair<int,int>> c;
        for(i=0;i<n;i++)
            {
          
            cin>>p.first;
            cin>>p.second;
            c.push_back(p);
        }
        
        if(n<=2)
            cout<<"YES\n";
        else
        if(n==3)
            {
            int x,y,xc=0,yc=0;
            x=c[0].first;
            y=c[0].first;
            
             for(i=0;i<n;i++)
                 {
                 if(c[i].first!=x)
                     {
                     xc++;
                     x=c[i].first;
                 }
                 if(c[i].second!=y)
                     {
                     yc++;
                     y=c[i].second;
                 }
                 
             }
            
            if(xc==2 || yc==2)
                cout<<"YES\n";
            else
                cout<<"NO\n";
        }
        else
            {
            sort(c.begin(),c.end());
            
            int x1,x2,y1,y2,flag=0,temp;
            
            x1=c[0].first;
            y1=c[0].second;
            x2=c[n-1].first;
            y2=c[n-1].second;
            
            
            
            for(i=0;i<n;i++)
                {
                 if(c[i].first>=x1 && c[i].first<=x2 && (c[i].second==y1 ||  c[i].second==y2))                   
                     flag=1;  
                else
                    if(c[i].second>=y1 && c[i].second<=y2 && (c[i].first==x1 || c[i].first==x2))
                    flag=1;
                else
                    {
                    flag=0;
                    break;
                }
                }
            if(flag==1)
                cout<<"YES\n";
            else
                cout<<"NO\n";
            
           
        }
          
        
    }
    return 0;
}